Possible to add also AIM2 second alarm support for DS3231

[martinberlin]

Hello Larry,
I would like to be able to add also support for AIM2 in this library for DS3231 RTC. Shall I make a PR or you can do it when you find some time?
Is not urgent. Just think it will be a nice addition to this great component.

[bitbank2]

adding it now...

[bitbank2]

I pushed a change which adds the ALARM 2 options; please let me know if it works. The alarm names are now:

// Alarm types
enum {
ALARM_SECOND=0,
ALARM_MINUTE,
ALARM_HOUR,
ALARM_TIME,
ALARM_DAY,
ALARM_DATE,
ALARM2_MINUTE,
ALARM2_HOUR,
ALARM2_TIME,
ALARM2_DAY,
ALARM2_DATE,
};

[martinberlin]

Thanks for the effort Larry. Looked at your commit and it looks perfect.
Just need to find time over the weekend to test it since with the C5 my DS3231 design was bad (Does not like to be powered by VBAT and get I2C pulled up to 3V3, my bad!)
It seems for the record RV3032 is more tolerant with that and you can power it from battery directly and still communicate with the I2C at a 3.3V logical level.