Merge polygon code from Dmitry Olshansky

[fryguybob]

(Imported from http://code.google.com/p/diagrams/issues/detail?id=2. Original issue from byor...@gmail.com on December 23, 2010, 10:17:07 PM UTC)

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.

[fryguybob]

(Imported. Original comment by byor...@gmail.com on December 27, 2010, 12:23:20 AM UTC)

There are a bunch of stubs in D.TwoD.Shapes now; search for 'writeMe'.

[fryguybob]

(Imported. Original comment by byor...@gmail.com on May 10, 2011, 06:55:07 PM UTC)

Dima sent me some code, I need to find some time to merge it into the existing repo.

[fryguybob]

(Imported. Original comment by byor...@gmail.com on June 19, 2011, 05:44:52 PM UTC)

Here's the code from Dima. Someone needs to go through, clean it up, and decide what pieces we can/should merge into the Shapes module.

[fryguybob]

(Imported. Original comment by byor...@gmail.com on September 2, 2011, 03:55:53 PM UTC)

Fri Sep 2 11:51:32 EDT 2011 Brent Yorgey byorgey@cis.upenn.edu

• Massive refactoring of Polygons module, and finally remove all polygon
  functionality from Shapes. This closes BoundingBox is now Monoidal #2; most of the code in
  Polygons is originally based on code written by Dmitry Olshansky
  (thanks Dima!).

  This is somewhat of a disruptive change since the type of the
  'polygon' function has changed. However, I hope users will find the
  new version much more expressive.

  Next steps:

1. Update all existing examples to compile again.
2. Add a number of functions to the Shapes module to construct
   various common shapes using the tools provided by Polygons, to
   give users more easy ways to do common things without needing the
   full generality of the polygon function.