draw mark marktype x y size
Draws a marker of type marktype at position
x, y at the requested size.
The marktype may be one of the following:
0 - none 1 - plus sign 2 - open circle 3 - closed circle 4 - open square 5 - closed square 6 - multiplication sign 7 - open diamond 8 - open triangle 9 - closed triangle 10 - open circle with vertical bar 11 - closed circle with vertical bar
12 - closed diamond (version 2.1+)