Version change from 5.1.0 to 5.0.1.
Version change from 5.1.0 to 5.0.1.

There was a difference of opinion on this issue but everyone was ultimately
willing to go along with a change in version from 5.1.0 back to 5.0.1 to
reflect that most of our work since 5.0.0 has been bug fixing (stable
releases with even minor numbers) rather than innovation (experimental
releases with odd minor numbers).

svn path=/trunk/; revision=2429

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