This is a big change that break compatiblity with existing applications
*and* with existing installed versions of main.py.
When upgrading it is import to update main.py:
./tools/wasptool --upload wasp/main.py
Moving it from applications into the watch is useful for two reasons.
Firstly it means applications don't need to know as much about the
display color depth and secondly it makes it easier to replace the
drawing routines with wasptool.
