Resolve WB-659: Palette color mapping is incorrect with interpolation and...

Resolve WB-659: Palette color mapping is incorrect with interpolation and 'none' color.  When interpolating colors and the data values was less than the 'none' color and above the next color, interpolation was using the 'none' color which produced incorect coloring as it used the RGB values assigned to the none color.  Logic has been corrected, in this case to apply no coloring in this situation.  Palettes affected are PSYCH, ROY-BIG, clear_brain, fidl, raich4_clrmid, raich6_clrmid, HSB8_clrmid, and POS_NEG.  By the way the problem was noticed when using the PSYCH palette and shades of blue were seen for positive values.