Blender Git Loki

bugfix [#25082] minor bug. RGB to Intensity doesn't works for Lamps
- This is working correctly but confusing, made more confusing by UI problems, corrected these and updated tooltop for 'tex.use_rgb_to_intensity'
- bad RNA arguments used for lamps (left over from RNA renaming).
- use isinstance(...), rather then comparing type() directly, this failed with lamp type checks.
- removed redundant argument to internal texture UI function factor_but().
- the texture color was drawn inactive when it was used in some cases.

Note. AFAIK its not possible to do a general check to see if a texture is colored or not, eg: its possible a plugin texture returns color in some cases and greyscale in others.
so for now always have color button active.