matplotlib Code

Revert the DraggableRectangle exercise solution to use the Rectangle.xy attribute now that it exists. This agrees with the exercise description.

Re-add the xy attribute to the Rectangle class (disappeared during the transforms refactor).

Fix bug in zoom rectangle with twin axes

Minor docstring fix.

Adding a small script that demonstrates the utility of transform_angles method added in last
commit (from dmkaplan).

Added a method to class Transforms in transform.py that transforms
angles. The generic method uses a generic algorithm involving pushing
off from a group of locations to determine new angles. This should
work with almost any transform, but much quicker algorithms can be
found for affine transforms. These algorithms have not yet been added
though, so the generic method will be used until they are.

sqrtm implemented in scipy

Added unit handling for axhspan and axvspan.

Added custom colorbar ticking example, contributed by Scott Sinclair

Fix bug in font_manager.py that was printing math junk on the docbuild machine.