Blender Git Loki

WIP adding tiles between chunks and images.

Merge branch 'master' into temp-gpu-texture-partial-updates

use chunk where they aren't tiles.

Renaming tile to chunk. (Not completed)

Add struct between tiles and images.

Added correct API usage check.

Reduces the requirements of interface.

Removed unused code.

Multiple renames.

More tests and cleanups.

Added mark region dirty.

Replaced internal gputexture generation with new partial update.

WIP: Parial update skeleton.

WIP: partial update image.

Differential Revision: https://developer.blender.org/D13238

WIP: partial update image.

Adding a basic mechanism that should be able to register tiles and find
changes. Not possible yet to loop over the updated tiles.
Next task would be to include reference to imbuf to get the width/height
of the images.