[PythonCAD] Improved DWG Reader, Take 4

[Art Haas]

Hi.

I've modified the R13/R14 reader so it more closely matches the R15
reader, so now is a good time to make the reader again available for
testing. The cleanups removed a nasty global variable by adding a
method to the Dwg class for getting and setting the version of the DWG
file being examined. This version info is then set in the entity.

My quick testing on a couple of files works, so things look good from
here. Let me know if you would like the files.

Also, I've upgraded to Python 2.3.2 this weekend. My build is from the
Python CVS repo as of a day or two ago. As I'm now on Python 2.3 I
should start seeing any of the errors and warnings other people have
reported. Doing this upgraded made me re-install the pygtk stuff, and my
installation of that package, again from CVS, printed out a few warnings
I hadn't seen before regarding int/float values in GTK calls. These will
be fixed promptly.

As the last two months have been spent working on these DWG/DXF readers,
there hasn't been much work done on the PythonCAD code itself. I'm
hoping to change that over the next couple of weeks, as the DWG reader
seems to be at a point where it is feasible to begin working on a real
import mechanism of DWG files into PythonCAD. There are still many
entities in AutoCAD that don't exist in PythonCAD - ellipses and splines
are examples of that. I've wanted to add both, and now that the idea of
importing DWG data is at least possible, the addition of these new
entities into PythonCAD is due.

Hatching and printing are still not working, nor is there any sign that
development of either will change in the short-term future. :-(

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