Blender Git Loki

Cycles: Change code order for Image Data Types.

Now we have the 4 component ones first (float4, byte4, half4) followed by the 1 component ones (float, byte, half).
Makes code a bit more consistent and also reduces code a bit when enabling half support on GPU in next commit.

This also exposed a typo in half CPU images for 3D textures, which wasn't used yet, but good to have that one fixed anyway.