vere: refcount fixes

[dozreg-toplud]

Contains refcount fixes found in #1059 separately, so that #1059 only contains only refcount annotations.

Depends on #1079

---

List of fixes:

• by_all/by_any jets slammed the gate while keeping uncounted references to l_a and r_a
• skid/skim/skip held uncounted reference to i during slam.
• ames.c missing u3z in some branches
• http.c missing u3z in some branches, callbacks retained instead of transferring, which seems to be the protocol for callbacks
• term.c: leak fixes (_reck_orchid retains), direct atom assertion
• unix.c direct atom assertions
• dawn.c u3r_string retains, u3nc transfers (although not a big deal right now as dawn_fail is noreturn)
• king.c helpers transfer
• lord.c missing break in switch!
• mars.c jar leak
• pier.c tag is transferred (probably left from u3r_string transferring long time ago)