Preserve timestamps for cp of example source code to make subsequent rsync step more efficient.
Preserve timestamps for cp of example source code to make subsequent rsync
step more efficient.

Demand WWW_USER, WWW_GROUP, WWW_HOST, and WWW_DIR be non-empty.

Tweak commentary.


svn path=/trunk/; revision=8791

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