better comments in PQ
stop iterating over all tiles on board, only worry about tiles in the camera view
trying out canvas context  save/resore, rather than re-translating - seems to work well
make board.exists() a little more understandable
modulate the animation speed for Sprite, needs some cleaning up, but it works
added try/catch for now, there is a problem i think with the way the camera start/end are calculated
experiment with caching canvas drawings - might not add as much benefit as i thought
do not need to repeat frames now that i have animation speed working
faster and less obscure way of clearing canvas
use paul irishs requestAnimFrame for requestAnimationFrame fallbacks
using chrome FPS meter, no longer need my own