More shapes in D.TwoD.Shapes

[byorgey]

Need a collection of standard shapes. Try to use the existing path mechanisms whenever possible (the existing Box type is a bad example of the sort of thing that should be done, and should be removed and replaced with a path-based version).

An (inexhaustive) list of the shapes that should be available: regular polygons of any number of sides; 45-45-90 triangle; 30-60-90 triangle; stars parameterized by number of points and perhaps other size/shape parameters; rounded rectangles; rounded polygons in general.