jhatwich/layer comps+size

Posting for review, feedback and some help...

To use this feature add a layer comp and name it something like "overview.png"

Things seem to be working ok, but when we getPixmap for layer comps it doesn't seem to apply the scale settings.  There is a log message in renderer.js line 527 that reports settings I'd expect to scale a layer comp.

To show the bug add a layer comp named "200% overview.png"  You will see the pixmap settings adjusted accordingly, but the resulting image is not scaled up.