Make pygbag python window size responsive

[KingNook]

Context

It is ugly. I wish for it to be un-uglified. As mentioned in #5

Thoughts / Challenges

I'm not entirely sure where to fix this from.

I could try some sort of dynamic window dimensions in pygame, although this would then require some interaction with pygbag / html / js to grab the browser window size. Also, to deal with rotation (portrait / landscape on mobile) I may have to resize the grid. This pretty much gives all the context for that (and redrawing shouldn't be an issue once I've moved all the 'board drawing' methods from GridRenderer into one mega-method.