Background colors
Fix crazy races with collisions over bounce block

*  Simplify player collisions tremendously.
*  Also some code clean up.
*  Combine some logic and goToPoint() into a single updatePlayer() function.
*  BounceBlock calls updatePlayer() on killedBy to avoid races.
Merge branch 'master' into gh-pages

* master:
  Fix crazy races with collisions over bounce block
  Background colors