Function: plotcolor
Class: highlevel
Section: graphic
C-Name: rectcolor
Prototype: vLL
Help: plotcolor(w,c): in rectwindow w, set default color to c. Possible
 values for c are given by the graphcolormap default: factory settings
 are 1=black, 2=blue, 3=sienna, 4=red, 5=green, 6=grey, 7=gainsborough.
Doc: set default color to $c$ in rectwindow $w$.
 This is only implemented for the X-windows, fltk and Qt graphing engines.
 Possible values for $c$ are given by the \tet{graphcolormap} default,
 factory setting are

 1=black, 2=blue, 3=violetred, 4=red, 5=green, 6=grey, 7=gainsborough.

 but this can be considerably extended.
