Don't mix tabs and spaces in python code

[mb74]

Please replace alls tabs with 4 spaces. You should avoid mixing tabs and spaces. It is a good idea to only use spaces.
Using tabs in python can lead to bugs which are very hard to find.
For a quick code analysis Cython (www.cython.org) can be used:

for x in `find | grep py`; do echo "############### $x:"; cython $x; done

The above command line showed several problems in your code (Version 1.4.0).
With cython you can also improve the speed of time critical python code a lot.

[moimael (moimael)]

Agreed. I made the same proposal some times ago.