Support for board sizes other than 6 x 7

[tannerkrewson]

As it stands, we use an image file to display the yellow board. If we were to use canvas to generates that same shape, we could change the size of the board to be something other than 6 x 7 and use colors other than yellow, just by changing some variables.

It would be a lot of work, but it would create some interesting possibilities for new modes.