Have the SVGKSource subclasses respond to being copied.
Add init methods to SVGKSource's subclasses.
Create our own image from any SVGKImage passed to us based on copying the passed image's source.
Merge branch 'master' into arc

Conflicts:
	Source/SVGKSource.m
	Source/Sources/SVGKSourceData.m
	Source/Sources/SVGKSourceLocalFile.m
	Source/Sources/SVGKSourceURL.m
	XCodeProjectData/ImageRep/SVGKitImageRep.m