Python 3 port

[Salamandar]

There are still bugs, but this project needed a Python 3 port. That's starting now I guess.

I had to port to spaces because Python was complaining about mixed spaces and tabs. And spaces are considered as the preferred tabulation system in Py3.

[phw]

Just for reference, PR #475 was a previous attempt at this. I haven't compared, but it might be worth looking there and taking things that probably are missing in this PR.

Relevant issue is #487

[Salamandar]

I think you will have to make a "python3" branch where all our PR will be merged, so that it doesn't need a single big PR.

[dralley]

Feel free to reuse my work in the aforementioned PR, I don't mind. I tried to keep each individual change in it's own commit.

I would however suggest not changing all of the tabs to spaces, because it will make the PR impossible to review. It's probably only a couple of places that are mixing improperly.

If @kozec will allow it, a separate PR to convert tabs to spaces would be good, though.

Source on the Python language officially preferring spaces over tabs: https://www.python.org/dev/peps/pep-0008/#tabs-or-spaces

[st-review]

🤖 beep boop

I'm going to close this pull request as it has been idle for more than 90 days.

This is not a rejection, merely a removal from the list of active pull requests that is periodically reviewed by humans. The pull request can be reopened when there is new activity, and merged once any remaining issues are resolved.