python3 working in fork

[Maarten]

Hey,

I forked your project on github. It now works on python 3.

https://github.com/madebr/subdownloader

Main changes:
- general: Bumped version to 2.0.19
- gui: removed QVariant
- gui: abstracted out QString
- 2to3: abstracted out differences between python 2 and 3
- cli: use argparse instead of deprecated optparse
- cli: updated python-progressbar (to current git)
- cli: --proxy option uses hidemyass proxy if no argument is given (UNTESTED)
- modules: removed unused modules
- modules: removed bundled mmpython. It did not return any usable metadata, even on my python 2.
- modules: use pymediainfo as fallback (python-kaa-metadata does not work on python3)
- 2to3: abstracted out changes in api

For details, see the commit history.
I tried to make it as clear as possible.

It needs some good testing!

Thanks