Fixing some compatabality errors...

* SoundManager2 now stays out of the game's way.
* Fixed a bug where SM2 would crash Firefox (somehow).
* Fixed the game crashing before ending when WebGL disabled.
* Disabled WebGL on all but Chrome and IE10+ because performance.
Merge branch 'master' of github.com:hughsk/ludum-dare-26
Fix a pretty significant bug in controls

Forgot to listen for "keyup" on the arrow keys,
hence people were having trouble with moving around
at all!