Make the macro ENABLE_GLOBAL_IMAGE_CACHE_FOR_SVGKIMAGE_IMAGE_NAMED be in SVGKImage.m instead of in the header.
Implement functions that weren't available when image caching was disabled. These just print to the log that they aren't available, and they do nothing.
Trimming down the check for ENABLE_GLOBAL_IMAGE_CACHE_FOR_SVGKIMAGE_IMAGE_NAMED: it should always be defined, even if it's disabled.
Make imageWithData: available on OS X.
Adding logging functions to OS X's image getters.
Add a KVO observer for changes in the scale.
Check with the observer that the key being changed is either the domtree's viewport or the scale.
Merge branch 'master' into arc

Conflicts:
	Source/SVGKImage.h
	Source/SVGKImage.m