Blender Git Loki

bge camera actuator: -X and -Y axis

The camera actuator only allows to look the object from its front face.

Given that Blender takes -Y as the default forward orientation, the current
functionality doesn't let a camera to track an actor from behind.

This patch allows for -X and -Y axis tracking. This way a camera over the
shoulders of a character is possible (without resorting to rotate the
mesh/armature original orientation.

- patch reviewed by Campbell Barton, thanks