profile_gamma rewrite  & simple gui drop

Why this should be merged:
1. introspection will not work with modules using simple_gui out of the box
2. simple_gui is only used by this iop
3. Fixed bug in profile_gamma: gamma and linear are swapped (misplaced) for some time now (since there has been no bugreports, i silently swapped them back(it was discussed and agreed that it was right way). FIXME: is this module even used by anyone?)
4. profile_gamma is now does not clip to [0,1] (Unbounded processing)
5. OpenCL kernel is added for profile_gamma