Code refactor: make Transform always affine, dropping last row.

This save a little memory and copying in the kernel by storing only a 4x3
matrix instead of a 4x4 matrix. We already did this in a few places, and
those don't need to be special exceptions anymore now.

intern/cycles/render/object.h

@@ -135,7 +135,7 @@ protected:
 		/* Packed object arrays. Those will be filled in. */
 		uint *object_flag;
 		KernelObject *objects;
-		float4 *objects_vector;
+		Transform *objects_vector;
 
 		/* Flags which will be synchronized to Integrator. */
 		bool have_motion;