Colormap View enhancements

[low-sky]

A few things I've noticed:

• [x] Gamma value has too many decimal places
• [ ] Gamma slider doesn't update across shared sessions or in multiple views.
• [ ] Transform name doesn't update across shared sessions or in multiple linked Colormaps for a single image.
• [ ] Synchronize Colors also doesn't update in multiple views in shared session.
• [x] Cached text is visible on images.
• [x] Is Pixel Cache and Interpolation necessary for user views?
• [ ] Color map doesn't retain properties when switching between views.
• [ ] Data-based transform needed like histogram equalization or zscale. Suggest just stealing from ds9.

[low-sky]

Talking with Adam L., he suggests that a tabbed view may help save some real estate with high-level vs. low level options.