Need to provide benchmarks for color management

We need some means to estimate a level of performance of our
color management sub-system, and to verify that changes in this
area do not cause any performance degradation.

In particular, we need to measure following aspects:
- ColorConvertOp performance for images and rasters.
- rendering speed for images with non-sRGB color spaces.
- performance of access to profile data (tags and header fields)