CMake logic fix; turn OFF variable created by the option command in properly cached way.  Also improve messages and deal with white space issues.
CMake logic fix; turn OFF variable created by the option command in properly
cached way.  Also improve messages and deal with white space issues.


svn path=/trunk/; revision=8016

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