Blender Git Loki

Clean-up and refactor of current OCIO integration

- Cleaned up some files -- seems there were some wrongly resolved
conflicts which resulted into duplicated code in space_image.py
and some build configuration files.
- Store all color space related data (such as display device, view
transform and so) as strings, so it could easily be ported to new
OCIO configuration files and it'll be much more portable between
different configurations.

This required adding some look-ups to RNA associated with such
settings, but it's indeed the only way to do this. If it'll be
figured out such look-ups causes performance issues it's possible
to optimize this further using hash. So far it's only few elements
in list to be looked up.
- Added support of display device transformation from OCIO
configuration files. Display device is setting per-window and
different windows could have different display devices, so it's
possible to have one blender window opened on sRGB monitor and
another one on xyz projector.

Display device is ignored when using ACES ODT Tonecurve view
transform due to it's not an OCIO transformation. Probably it'll
be possible to get rid of this tone curve soon (if it'll be
proved useless or it'll be implemented as a part of OCIO LUT).
- Movie Cache now supports deleter functions for user keys, so
such keys could have some allocated data which would be removed
as soon as element in cache is being removed.
- Movie Cache now support callbacks to check whether current
cache element could be removed from a cache due to it wouldn't
be accessed anymore.
- Re-written cache stuff for display buffers of ImBuf. Now it's
using Movie Cache which is global for all ImBufs.

Probably it's not implemented in fastest way, would be investigated
further and probably changed it performance wouldn't be good enough.