Add  www-install-doxygen target which installs generated doxygen documentation to our website.
Add  www-install-doxygen target which installs generated doxygen
documentation to our website.

svn path=/trunk/; revision=11339

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