Bug 644032 - Color banding in Hue-Saturation with overlap

When calculating an overlap between two ranges, interpolate the hue
adjustment from config->hue[primary_range] and
config->hue[secondary_range] BEFORE mapping it to the input value.
This fixes odd edge cases where only one of the ranges crosses the
red/magenta wraparound, or if adjustments to different channels yield
more than 180 degree difference from each other.