Change plcolorbar labels to be consistent with name of option.
Change plcolorbar labels to be consistent with name of option.

Upper => Top
Lower => Bottom


svn path=/trunk/; revision=11535

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