e1a9c16176
This adds back the new mix node to the Color sections of the add node menu. The add menu now contains two entries for the mix node. One under Utilites/Converter which defaults for float. One under Color which defaults to color with `Mix Color` label. This was moved as part of D13749. The issue was reported on BlenderArtists. Differential Revision: https://developer.blender.org/D15887