cgol: (list (list ?)) -> bitmap library

[rabsef-bicrym]

cgol stores active game sessions as a game, below:

+$  game
  $:  %0
      size=[x=@ud y=@ud]
      step=@ud
      bord=board
  ==

Where a board is a (list (list ?)). This format affords us easy conversion to a bitmap image for mini-map views for selecting saved games.

Please write an arm in /lib/cgol/play/hoon $-((list (list ?)) bmp) where bmp is encoded such that it can be directly inserted into a sail page img tag as src.