Fix the rendering of some MarkGraphic instances.
The objects returned by WellKnownName#getShape were sometimes invalid.
Indeed, Arc2D, Ellipse2D and Rectangle2D expect to receive positive
width and height. Considering symmerties in these objects, I've tried to
use Math.abs when it was possible. The leftmost x-ordinate and the angle
of the HalfCircle have received a special treatment.