Fixed for histogram chart. No longer inserts a 'zero' bucket into the...

Fixed for histogram chart.  No longer inserts a 'zero' bucket into the histogram when zeros are not displayed.  Instead, Palette coloring is ALWAYS applied to the histogram since the palette coloring will use an alpha value of zero for data not colored.  If the user is using a solid color, it will be later applied and it will not modify the alpha values so that non-displayed histogram bars remain hidden.