Blender: Better algorithm for camera choice in stereo-3D rendering mode

STEREO_CAMERA parameter can be set to "Left" or "Right" to render corresponding "eyes".
Module checks for cameras "Left" and "Right".
If they are not exist, then it tries to use "CURRENT_CAMERA.Left" and "CURRENT_CAMERA.Right",
where CURRENT_CAMERA is the name of active camera.
Blender: Optimize Cycles rendering
Blender: Add "gpu_device" module configuration oprion

Allows to specify GPU device to use for Cycles rendering.