* Allow support for custom texture atlas formats other than PLIST.
* Revert usage of emplace_back to push_back to ensure support for older compilers.
* Update test to support SpriteFrameCache::addSpriteFramesWithFile
* Re-add SpriteFrameCache::addSpriteFramesWithFileContent
* Change order of SpriteFramesFromFileContent test back to what it previously was
* Remove sprite sheet and all frames associated with it correctly
* Move sprite loader classes into their own files to clean up CCSpriteFrameCache
* Remove redundant line and update comment
* Fix formatting to match adxe code style
* Fix typo
* Add custom sprite sheet loader test using JSON-array sprite atlas format.
Simplify sprite sheet loader interface by adding identifier to the custom sprite sheet loader implementation.
* Add newline at the end of the file
RH