Add clock AM/PM display code, fix ghost arms and phase offset

Add clock AM/PM display code, fix ghost arms and phase offset
* Fix the problem of ghost arms/arms not being cleared out
* Fix the issue wherein the angles are offset pi/2 from where they should be
* Add digital time indicator which partially works (says 00 instead of 12)
* Make the font "SMART WATCH OS" bold
* Reduce sampling period to 500 ms to allow regular 1s updates with no
  skips
* Add slower_baud to allow reducing baud rate back to 9600
* Allow lcd_clock_draw_hand to accept color