Blender Git Loki

Code refactor: Change Cycles ImageManager arrays.

This commit simplifies the code for the image arrays. Instead of having 2 arrays for float and byte textures,
we now use an array here. This simplifies the code (avoids code duplication), and makes it possible to easily extend it
with float1 and half-float types in the future.

Only tested with CPU yet, plus some cleanup / code de-duplication is still possible here.

Reviewers: #cycles, sergey

Reviewed By: #cycles, sergey

Subscribers: jesterking, sergey

Differential Revision: https://developer.blender.org/D1969