[PythonCAD] More fixes for DimString modification at repo

[Art Haas]

Hi.

I've sent a couple of fixes for DimString modification to the repo, and
it looks like this is the last set of changes to go in before I make the
release, most likely tomorrow. People using subversion can get these
fixes with an 'svn update'.

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