Added DTCoreTextMacros.h header.
Added objc_returns_inner_pointer attribute to -CGColor method on MacOSX target. This will match AppKit and UIKit definition and fix a memory leak in our implementation.
Fixed DT_RETURNS_INNER_POINTER definition.
Merge pull request #771 from jcbertin/develop

Fix memory leak in -CGColor method on MacOSX target.