[PythonCAD] Updated DWG reading program

[Art Haas]

Hi.

I've fixed the fix found bug in the 'dwg.py' file - decoding the class
data info did not handing padding bits correctly. I've also changed the
way handles are stored in the file. Now they are tuples of integers.

Let me know if you want this file to test on your R13/R14 drawings.
Feedback is appreciated.

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