diff --git a/Cargo.lock b/Cargo.lock
index a9886cb..1ec051d 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -33,7 +33,7 @@ name = "approx"
 version = "0.3.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "num-traits 0.2.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "num-traits 0.2.12 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -49,6 +49,11 @@ name = "autocfg"
 version = "0.1.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
+[[package]]
+name = "autocfg"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
 [[package]]
 name = "backtrace"
 version = "0.3.13"
@@ -426,8 +431,8 @@ dependencies = [
  "jpeg-decoder 0.1.15 (registry+https://github.com/rust-lang/crates.io-index)",
  "lzw 0.10.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "num-iter 0.1.37 (registry+https://github.com/rust-lang/crates.io-index)",
- "num-rational 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "num-traits 0.2.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "num-rational 0.2.4 (registry+https://github.com/rust-lang/crates.io-index)",
+ "num-traits 0.2.12 (registry+https://github.com/rust-lang/crates.io-index)",
  "png 0.12.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "scoped_threadpool 0.1.9 (registry+https://github.com/rust-lang/crates.io-index)",
  "tiff 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -479,7 +484,7 @@ name = "line_drawing"
 version = "0.7.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "num-traits 0.2.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "num-traits 0.1.43 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -563,21 +568,22 @@ name = "num"
 version = "0.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "num-bigint 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "num-bigint 0.2.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "num-complex 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "num-integer 0.1.39 (registry+https://github.com/rust-lang/crates.io-index)",
+ "num-integer 0.1.43 (registry+https://github.com/rust-lang/crates.io-index)",
  "num-iter 0.1.37 (registry+https://github.com/rust-lang/crates.io-index)",
- "num-rational 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "num-traits 0.2.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "num-rational 0.2.4 (registry+https://github.com/rust-lang/crates.io-index)",
+ "num-traits 0.2.12 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
 name = "num-bigint"
-version = "0.2.2"
+version = "0.2.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "num-integer 0.1.39 (registry+https://github.com/rust-lang/crates.io-index)",
- "num-traits 0.2.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "autocfg 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "num-integer 0.1.43 (registry+https://github.com/rust-lang/crates.io-index)",
+ "num-traits 0.2.12 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -585,7 +591,7 @@ name = "num-complex"
 version = "0.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "num-traits 0.2.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "num-traits 0.2.12 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -593,7 +599,7 @@ name = "num-derive"
 version = "0.2.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "num-traits 0.2.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "num-traits 0.2.12 (registry+https://github.com/rust-lang/crates.io-index)",
  "proc-macro2 0.4.26 (registry+https://github.com/rust-lang/crates.io-index)",
  "quote 0.6.11 (registry+https://github.com/rust-lang/crates.io-index)",
  "syn 0.15.26 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -601,10 +607,11 @@ dependencies = [
 
 [[package]]
 name = "num-integer"
-version = "0.1.39"
+version = "0.1.43"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "num-traits 0.2.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "autocfg 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "num-traits 0.2.12 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -612,18 +619,19 @@ name = "num-iter"
 version = "0.1.37"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "num-integer 0.1.39 (registry+https://github.com/rust-lang/crates.io-index)",
- "num-traits 0.2.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "num-integer 0.1.43 (registry+https://github.com/rust-lang/crates.io-index)",
+ "num-traits 0.2.12 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
 name = "num-rational"
-version = "0.2.1"
+version = "0.2.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "num-bigint 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
- "num-integer 0.1.39 (registry+https://github.com/rust-lang/crates.io-index)",
- "num-traits 0.2.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "autocfg 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "num-bigint 0.2.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "num-integer 0.1.43 (registry+https://github.com/rust-lang/crates.io-index)",
+ "num-traits 0.2.12 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -631,13 +639,16 @@ name = "num-traits"
 version = "0.1.43"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "num-traits 0.2.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "num-traits 0.2.12 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
 name = "num-traits"
-version = "0.2.6"
+version = "0.2.12"
 source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "autocfg 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
+]
 
 [[package]]
 name = "num_cpus"
@@ -661,7 +672,7 @@ name = "ordered-float"
 version = "1.0.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "num-traits 0.2.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "num-traits 0.2.12 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -1075,7 +1086,7 @@ dependencies = [
  "byteorder 1.2.7 (registry+https://github.com/rust-lang/crates.io-index)",
  "lzw 0.10.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "num-derive 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)",
- "num-traits 0.2.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "num-traits 0.2.12 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -1229,6 +1240,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum approx 0.3.1 (registry+https://github.com/rust-lang/crates.io-index)" = "3c57ff1a5b00753647aebbbcf4ea67fa1e711a65ea7a30eb90dbf07de2485aee"
 "checksum arrayvec 0.4.10 (registry+https://github.com/rust-lang/crates.io-index)" = "92c7fb76bc8826a8b33b4ee5bb07a247a81e76764ab4d55e8f73e3a4d8808c71"
 "checksum autocfg 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)" = "a6d640bee2da49f60a4068a7fae53acde8982514ab7bae8b8cea9e88cbcfd799"
+"checksum autocfg 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)" = "f8aac770f1885fd7e387acedd76065302551364496e46b3dd00860b2f8359b9d"
 "checksum backtrace 0.3.13 (registry+https://github.com/rust-lang/crates.io-index)" = "b5b493b66e03090ebc4343eb02f94ff944e0cbc9ac6571491d170ba026741eb5"
 "checksum backtrace-sys 0.1.28 (registry+https://github.com/rust-lang/crates.io-index)" = "797c830ac25ccc92a7f8a7b9862bde440715531514594a6154e3d4a54dd769b6"
 "checksum bitflags 1.0.4 (registry+https://github.com/rust-lang/crates.io-index)" = "228047a76f468627ca71776ecdebd732a3423081fcf5125585bcd7c49886ce12"
@@ -1292,14 +1304,14 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum nix 0.12.0 (registry+https://github.com/rust-lang/crates.io-index)" = "921f61dc817b379d0834e45d5ec45beaacfae97082090a49c2cf30dcbc30206f"
 "checksum nodrop 0.1.13 (registry+https://github.com/rust-lang/crates.io-index)" = "2f9667ddcc6cc8a43afc9b7917599d7216aa09c463919ea32c59ed6cac8bc945"
 "checksum num 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "cf4825417e1e1406b3782a8ce92f4d53f26ec055e3622e1881ca8e9f5f9e08db"
-"checksum num-bigint 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)" = "57450397855d951f1a41305e54851b1a7b8f5d2e349543a02a2effe25459f718"
+"checksum num-bigint 0.2.6 (registry+https://github.com/rust-lang/crates.io-index)" = "090c7f9998ee0ff65aa5b723e4009f7b217707f1fb5ea551329cc4d6231fb304"
 "checksum num-complex 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)" = "107b9be86cd2481930688277b675b0114578227f034674726605b8a482d8baf8"
 "checksum num-derive 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)" = "8af1847c907c2f04d7bfd572fb25bbb4385c637fe5be163cf2f8c5d778fe1e7d"
-"checksum num-integer 0.1.39 (registry+https://github.com/rust-lang/crates.io-index)" = "e83d528d2677f0518c570baf2b7abdcf0cd2d248860b68507bdcb3e91d4c0cea"
+"checksum num-integer 0.1.43 (registry+https://github.com/rust-lang/crates.io-index)" = "8d59457e662d541ba17869cf51cf177c0b5f0cbf476c66bdc90bf1edac4f875b"
 "checksum num-iter 0.1.37 (registry+https://github.com/rust-lang/crates.io-index)" = "af3fdbbc3291a5464dc57b03860ec37ca6bf915ed6ee385e7c6c052c422b2124"
-"checksum num-rational 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)" = "4e96f040177bb3da242b5b1ecf3f54b5d5af3efbbfb18608977a5d2767b22f10"
+"checksum num-rational 0.2.4 (registry+https://github.com/rust-lang/crates.io-index)" = "5c000134b5dbf44adc5cb772486d335293351644b801551abe8f75c84cfa4aef"
 "checksum num-traits 0.1.43 (registry+https://github.com/rust-lang/crates.io-index)" = "92e5113e9fd4cc14ded8e499429f396a20f98c772a47cc8622a736e1ec843c31"
-"checksum num-traits 0.2.6 (registry+https://github.com/rust-lang/crates.io-index)" = "0b3a5d7cc97d6d30d8b9bc8fa19bf45349ffe46241e8816f50f62f6d6aaabee1"
+"checksum num-traits 0.2.12 (registry+https://github.com/rust-lang/crates.io-index)" = "ac267bcc07f48ee5f8935ab0d24f316fb722d7a1292e2913f0cc196b29ffd611"
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 "checksum ordered-float 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)" = "2f0015e9e8e28ee20c581cfbfe47c650cedeb9ed0721090e0b7ebb10b9cdbcc2"