Blender Git Loki

Upgrades to the UVProject modifier:
- New perspective projection capability. If a camera is used as the
projection object, the modifier detects whether to do perspective or
orthographic projection based on the camera type. If any other object
type is used as the projection object, orthographic projection is used.
- Orthographic projection actually works properly now.
- The projected UVs are scaled and offset so that the image is centred in
the projecting camera's view.
- AspX and AspY inputs have been added to control the aspect ratio of the
projected UVs.

Also:
- I have added the Mat4MulVec3Project() function to BLI_arithb.h; this
function converts a 3-dimensional vector to homogeneous coordinates
(4-dimensional, with the 4th dimension set to 1), multiplies it with the
given matrix, then projects it back to 3 dimensions by dividing through
with the 4th dimension. This is useful when using projection matrices.