Avoid unnecessary null transforms
Canvas drawing loop improvements

Use plain for loop, use direct _x, _y properties where possible.
Add support for image smoothing param

Set it to false when woking with pixel art. False might lead to better performance, since it would use cheaper interpolation algorithms. It might not make a big difference on GPU backed canvases.
Improve get bounding client rect

Remove forEach, direct accessors
Add shallow parameter to group boundingClientRect
Only set opacity flag if there is an actual difference
This whitespace annoys me when building and diffing
Merge pull request #113 from DieBuche/smallImprov

Small improvements