Change the logic of the previous bug fix so the test for what to do with the plcont case is now identical to the test (pltr && pltr_data) done inside plshade.
Change the logic of the previous bug fix so the test for what to do with the
plcont case is now identical to the test (pltr && pltr_data) done inside
plshade.

svn path=/trunk/; revision=5070

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