Your own fonts, and a steadier clock.

* Add fonts from a file. They are kept inside the app, so no storage permission is
  asked for, and the font survives you moving or deleting the original. Keep several,
  see what they occupy, delete any of them.
* The hour, minute, seconds, weekday, month-and-day and year each take their own font.
* Bold, italic and underline.
* Every field is now sized from the widest text it could ever show, so the clock no
  longer resizes or shifts as the digits change. 11:11 sits exactly where 88:88 would.
* Burn-in protection covers a wider area, moving a few pixels each minute.
