TimezoneConverter Updates.

- Minor refactor with a move to named captures.
- Add support for "from" keyword on input timezone.

Fixes #631.
Yes, the int is incredibly relevant.  Insanely, this does conversions by floating-point hours.  So 12:20 will look something like 12.33333333 here.  Since I don't want to subtract 12 for any times in the 12 o'clock hour.. here we are.