Added new Tcl API functions plscol0 and plscolbg for color setting.
Added new Tcl API functions plscol0 and plscolbg for color setting.

svn path=/trunk/; revision=1598

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