WIP: Update to python 3 and anki 2.1

[j-kramer]

I ported this project to Python 3 and Anki 2.1. All the test pass locally and I've been using this PR for about month without much of an issue. However there a still a few caveats, so feedback is appreciated.

1. This PR was not tested on locales other than UTF-8.
2. It is not a backwards compatible with Anki 2.0.
3. My solution (kanjicolorizer/colorizer.py lines 34-43) to importing the argparser and colorsys dependencies, if kanjicolorizer is part of the Anki addon, is probably a hack. From what I understand the issue is that python 3+ does not support implicit relative imports anymore. My current solution catches the exception and imports them with an explicit relative import instead. I considered using the build system to patch the imports, but I'm not sure that is any better either. Maybe there is a better solution but my knowledge of python is rather limited.

In light of these issues how do we proceed on this PR?

edit: I forgot about cicleci: it uses python 2.7 instead of 3 so the tests fail.

[cayennes]

Thanks! Sorry I'm so slow at getting to this.

1. needs to be done - it was a while ago now, but my recollection is that the first version of this that I released was broken for many people because I failed to test on non-utf-8 locales. I'll try to get to this but it won't be within the next couple weeks, and if you could do it that would be great. Testing on all three major operating systems would also be good for significant changes like this.
2. is to be expected; we can release two separate versions
3. is a perfectly acceptable hack in the interest of getting this out

[j-kramer]

I only have linux pc's, so I can't test the changes on the other operating systems. I did a quick test for non-utf-8 locales by starting anki with the C locale:

$ LANG=C anki
Traceback (most recent call last):
...
Exception: Anki requires a UTF-8 locale.

So at least for anki non-utf-8 locales are not an issue anymore. This leaves the doc-tests and unit-tests, which both pass with LANG=C.

[cayennes]

Thank you so much for this! I'm finally getting to it this week, and it's really great to have this pretty much done. I've successfully tested it on linux and windows so far, and I have just some small additions to make before I'll merge it to master and release it it.