Ellipse et al

Could we have Ellipse added to the basic set of blocks for Diagram objects? There seems to be a distinct lack of ellipse based drawing elements such as chords, pies, crescents (with control handles to change the angle of these shapes.

Other basic shapes would also be handy such as a triangle (right, equilateral, scalene, and irregular), some regular polygons (i.e. identical angles and sides), and other shapes with lines of symmetry such as parallelograms, trapezoids that work similar to arrows (control boxes).

While I can make all of these by descending and registering new classes, it takes time that I don't have, this is made worse by having no API documentation other than existing code meaning I will end up spending 5x as long as what it should take.