Make Python 3.x compatible

[mahlzahn]

Siehe osmapi/tree/py3develop, but not tested, just 2to3 used.

[metaodi]

The idea would be to have a library that actually works on Python 2 & 3 (i.e. not just convert the code). But thanks for the hint :wink:

[mahlzahn]

Yes, this is a good idea. I have two reading suggestions:

• Porting Python 2 Code to Python 3 in the offical python docu,
• Six, a Python 2 and 3 Compatibility Library.

[metaodi]

This issue was solved by PR #15