[Gzz] Python code conventions?

[Vesa Kaihlavirta]

Just a little thing: I've noticed that almost all of our python-files
are contaminated with indentation that uses both tabs and spaces. This
makes some editors to show indentations incorrectly, which in pythonese
means that the program looks wrong.

So we should decide whether to use ONLY tabs or ONLY spaces, and after
resolution, never go back to using both. Perhaps a test that runs
python -tt or equivalent on all python-code?

--
V.K.