[PythonCAD] More changes at the repo, release coming shortly

[Art Haas]

Hi.

I've added more changes to the code, and made them available at the
repo. There are a few undo/redo changes, and a number of other smaller
changes fixing various bugs. The drawing of tangent circles was messed
up, and now that should be fixed. There was also a number of bugs that
were tripped when a file was saved, and they've been fixed.
Unfortunately I broke the file saving code prior to the release last
month, and the bug is just now fixed, so things have been broken for
quite some time. I'll be making a release probably tomorrow or Thursday
so that the fixes are available to people downloading the tar archives.
Subversion users can get them by simply doing 'svn update'. I'd planned
to do a little more work before making the release, but the file save
bugs are speeding things up.

Art
-- 
Man once surrendering his reason, has no remaining guard against absurdities
the most monstrous, and like a ship without rudder, is the sport of every wind.

-Thomas Jefferson to James Smith, 1822