Blender Git Loki

Color management refactor

- Move color management display settings into own structure like it's
done for view settings.

This is helpful from two sides:

* It is planned to support display calibration settings which
should be taken into account by color management stuff to
add needed transformations to OCIO processor.
* File saving should be able to make the same display
transformations as it's done by window when displaying the image.
Having own DNA and RNA structures for display device settings
helps avoiding having duplicated code.

- Small refactor of cacheing functions which are now accepts
cache-like versions of view and display settings. This structures
used for cache are quite the same as DNA structures but they contains
indices of view and display which avoids extra lookup for this
things.

This also helps having reasonable amount of variables passing
to cache functions.