Blender Git Loki

Color management refactoiring and some extra options

- Move space-being settings (such as view transform) into own
DNA and RNA structure to avoid code duplication in some areas
and save some arguments on display buffer acquiring function.

Also added some utility functions to BKE to manipulate this
settings.

- Replace static sized color managed buffer flags array with
dynamically sized array which matches actual number of displays.

Probably this flags better be transfposed so it'll support
any number of view transforms and 32 displays (currently it's
other way around). it's runtime flags only, so would be simple
to change any time.

- Added support of configurable exposure and gamma.

Changing this settings wouldn't generate new item in cache,
it'll affect on buffer with the same color spaces conversion.

It'll also run full color transform from scratch on every run,
this could be changes in a way that it'll re-use color managed
buffer, but from quick glance it doesn't give really noticeable
boost.

Currently this settings are stored as pointer in ImBuf structure
itself. Probably it make sense removing them from ImBuf and make
moviecache be able to store some kind of tags associated with
cached ImBuf.