Added python3 support

[xarkes]

This pull requests adds python3 support while keeping python2 compatibility.
Please note that it works for my needs for adding lighthouse to https://github.com/radareorg/cutter however I did not really try it on other disassembler with python2, so I suggest to heavily test it before :)

[gaasedelen]

Sorry for the merge conflicts on the dev branch. I started to re-architect some stuff, and there is more coming 😅. I'll try to merge your stuff in before my commit storm hits. I should have some time to test it tonight and tomorrow.

I am also kind of surprised. This is fewer changes than I thought Py3 compatibility was going to take. It was also on the roadmap for the few binja users that choose to use a Python 3 interpreter (#62)

[gaasedelen]

I had a chance to look at this today and will not accept it outright.

My chief complaint is the use of six. Lighthouse does not require any external dependencies at this time, and I would prefer to keep it that way for user convenience.

Considering how few items we need from six, it is best we just create our own shim :-). I went ahead and did this. It appears to be working in my IDA/Python 2.7 env, but I don't have Binja on Py 3.x (or your cutter changes).

Care to test??

[gaasedelen]

I switched my Binja env over to 3.6 and got it set up with PyQt5. Needed a few more fixups, but seems to work.

Good enough for dev ¯\_(ツ)_/¯