Implement interpretation of sign of x and y legend offsets that depends on the PL_LEGEND position bits that are set.
Implement interpretation of sign of x and y legend offsets that
depends on the PL_LEGEND position bits that are set.

svn path=/trunk/; revision=11309

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