[PythonCAD] DWG reader update

[Art Haas]

Hi.

A short note to thank the people who sent me DWG files, and to let
people know that these files have been incredibly useful in flushing out
bugs. Numerous bugs have been fixed today thanks to these test files.

Please keep testing and sending files that fail - if you can.

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