python3 support

[manu-chroma]

since, the project has no dependencies, it should be relatively easy to extend support for python3.

something like 2to3 can come in really handy. https://docs.python.org/2/library/2to3.html

[nmoya]

Even better than that, we could write it in Python 2 and 3. at this point, I think it should be trivial to fix the minor details that block us from running python 3. https://wiki.python.org/moin/PortingToPy3k/BilingualQuickRef