[PythonCAD] Bug in Generic/dwg15.py in latest PythonCAD release

[Art Haas]

Hi.

I found a dumb bug in the dwg15.py file that went out with the latest
release. The 'get_default_double()' function needs to have 'dwgutil'
added as a prefix. This change is easy to do in a text editor. Simply
search for 'get_default_double' and prepend 'dwgutil.' to it.

Sorry about letting this slip by ...

-- 
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