Fix/Audit Medium definitions on the Camera.

[shadeops]

Define the medium before the camera, not after. If we want to allow anything other than a homogeneous we need to apply a transform relative to the camera's transform. Also the colorspace should be reset if one is applied.

[shadeops]

Addressed with cfcec44807f5ca2a5c1fc11c507b91d17757e1e7