Blender Git Loki

fix BGE bug #8646: unusable anaglyph settings

The best rules for stereo rendering are now applied to Blender. Here is the new situation:
1) The focal distance is now settable through the GUI: select the camera (each camera can have a different setting) and go to the camera data (F9): the "Dof Dist" and "Dof Ob" can be used to set the focal distance for that camera. The "Dof Ob" is interesting because it sets the focal distance so that the center this object will appear at the surface of the screen when running the game.
2) The eye separation is automatically set to focal_distance/30, which is considered to be a reasonable value. If you need a different value, you can always use Python scripting.

Notes:
- If you switch camera during the game, the focal distance will also change unless you have set the focal distance by scripting, in which case it overwrites the focal distance setting of all cameras.
- If you don't set the focal distance in the camera data or by scripting, the default value will be used. The default value corresponds more of less to the near clipping plane which means that all the objects will be very far with little 3D effect.
- If you don't set the eye separation by scripting, it is automatically computed as focal_distance/30, regardless on how the focal distance was set.