Color Management, Stage 2: Switch color pipeline to use OpenColorIO

Replace old color pipeline which was supporting linear/sRGB color spaces
only with OpenColorIO-based pipeline.

This introduces two configurable color spaces:

- Input color space for images and movie clips. This space is used to convert
  images/movies from color space in which file is saved to Blender's linear
  space (for float images, byte images are not internally converted, only input
  space is stored for such images and used later).

  This setting could be found in image/clip data block settings.

- Display color space which defines space in which particular display is working.

  This settings could be found in scene's Color Management panel.

When render result is being displayed on the screen, apart from converting image
to display space, some additional conversions could happen.

This conversions are:

- View, which defines tone curve applying before display transformation.
  These are different ways to view the image on the same display device.
  For example it could be used to emulate film view on sRGB display.

- Exposure affects on image exposure before tone map is applied.

- Gamma is post-display gamma correction, could be used to match particular
  display gamma.

- RGB curves are user-defined curves which are applying before display
  transformation, could be used for different purposes.

All this settings by default are only applying on render result and does not
affect on other images. If some particular image needs to be affected by this
transformation, "View as Render" setting of image data block should be set to
truth. Movie clips are always affected by all display transformations.

This commit also introduces configurable color space in which sequencer is
working. This setting could be found in scene's Color Management panel and
it should be used if such stuff as grading needs to be done in color space
different from sRGB (i.e. when Film view on sRGB display is use, using VD16
space as sequencer's internal space would make grading working in space
which is close to the space using for display).

Some technical notes:

- Image buffer's float buffer is now always in linear space, even if it was
  created from 16bit byte images.

- Space of byte buffer is stored in image buffer's rect_colorspace property.

- Profile of image buffer was removed since it's not longer meaningful.

- OpenGL and GLSL is supposed to always work in sRGB space. It is possible
  to support other spaces, but it's quite large project which isn't so
  much important.

- Legacy Color Management option disabled is emulated by using None display.
  It could have some regressions, but there's no clear way to avoid them.

- If OpenColorIO is disabled on build time, it should make blender behaving
  in the same way as previous release with color management enabled.

More details could be found at this page (more details would be added soon):
http://wiki.blender.org/index.php/Dev:Ref/Release_Notes/2.64/Color_Management

--
Thanks to Xavier Thomas, Lukas Toene for initial work on OpenColorIO
integration and to Brecht van Lommel for some further development and code/
usecase review!

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@50628 954f8c5b-7b00-dc11-b283-0030488c597c