Fix circle rendering in canvas
Fix circles with image fills in canvas
Fix problem with the stroke line position
Create JS canvas for Frame fill even if CSS canvas is supported.

#126
Use only CSS canvas for frame fill if possible.
Merge branch 'frame-background-canvas'
Fixes #126
Merge remote-tracking branch 'aurhe/canvas-circle-fix'
Do not require lime.RoundedRect to be present for Image fill to work.