Correct versioning check for manipulator
Fix compilation of Cycles AVX kernel with cmake.
Adding theme colors for tabs.

This adds theme colors for tabs, allowing better user control over the style. In particular this helps address issues with transparent regions and/or dark themes. The previously interpolated colors made it difficult to get a good balance of colors with many theme styles.

In addition, this updates the default theme to set the 3D View toolbar background color to opaque, rather than transparent.