First attempt at Python3 compatibility

[warrickball]

I just worked through all the Python3 errors until I got something working. Broad changes include:

• brackets for print statements,
• casting iterables as lists so they can be added, and
• removing dictionary sorts, which seem to be unsupported in Python 3.

So far (at least with my code) it appears to preserve Python 2 functionality (except for the loss of those dict.sort() statements).

[stefraynaud]

Hi @warrickball

I merged you PR into the python3 branch.

Thanks alot.