This new plugin lets us store a default palette and colormap in PROGMEM.
Rather than teaching Colormap to pull from either EEPROM or PROGMEM, this
implements an entirely separate plugin, `DefaultColormap`, which is able
to *push* a palette and colormaps into Colormap.
When `DefaultColormap.setup()` is called, it checks if Colormap's storage area
is empty (both palette and the map must be empty), and if so, copies the
built-in palette and colormap over, and forces a refresh, and it has done its
job.
It does provide an additional Focus command too, `colormap.install`, which will
forcibly copy both palette and colormaps over. Useful for resetting back to a
factory setting.
Signed-off-by: Gergely Nagy <algernon@keyboard.io>