3.x port

[AkagiShiroe]

maybe you're interested? or still want to retain 2.x code

[mauzel]

Thanks for the effort to port the code to Python 3.x. I guess porting to Python 3.x needs to eventually be done so now is probably as good a time as any other.

However, many of the changes in this pull request are code formatting. Do you think you can separate the code formatting changes and Python 3.x port changes?

For code formatting, I plan on enforcing an auto-formatter so that any code formatting issues can be simply resolved.

Edit: It would also be nice if you could rebase your Python 3.x port commits into a single commit (without the code formatting changes).

[AkagiShiroe]

code formatting nee~ let me redo the whole stuff (i still remember which code for port)