An auxiliary function to plot squares, used by the
plot.factorplot function
squares(ll, width = 1, col)A square is printed on the graph, but nothing else is returned
The (x,y) coordinate of the lower-left corder of the
square
a scalar indicating how wide the squares should be
a color with which the square will be filled in
Dave Armstrong
This is a function called by plot.factorplot and not intended
to be directly used by the user; however, it is possible that this could be
of more general use as a utility. The function is simply a wrapper to
polygon that obviates the need to specify all (x,y)
coordinates for the polygon.