Slice take2

[Geokureli]

WIP, this is a really old branch that needs testing

TODO:

• Fix worldToFrameHelper, viewToFrameHelper and worldToFrameSimpleHelper to work with frame slicing
• Fix scale/origin display positioning
• Fix issue where slice rects are not rendered when their unstretched region is off-screen
• Allow sections to be tiled rather than scaled
• Test with different animations/ multiple frames
• Unit tests