Fixed Visual handling to support grayscale and mono displays.  Enabled exporting of colormap hack flag for other files (plframe.c) that need it.
Fixed Visual handling to support grayscale and mono displays.  Enabled
exporting of colormap hack flag for other files (plframe.c) that need it.

svn path=/trunk/; revision=951

FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot