Fullscreen mode; scaling; background now drawn on canvas
closes #63
CAUTION: Due to scaling, Game.transformedSize should now ALWAYS be used
instead of Stage.canvas.clientWidth/height or anything else of that sort.
If you're confused why that is, review this commit and if it's still
unclear, ask Stopa

Contains considerable performance drop due to much more collidable
objects. Hopefully will be resolved by refactoring collision in near
future.
Merge branch 'master' of github.com:Stopa/Mobile-Defence-Fortress