Add support for neovim, newest pudb and atomize python code

[Elkasitu]

Neovim v0.2.0 support added (tested), shouldn't break vim support (not tested)

Newest pudb requires that bp objects contain a cond attribute, if they don't the program breaks and you get a traceback, solution for now is to assign None to self.cond during BP init, which works but is not ideal if anyone wants to actually add a BP condition.

Python code is now within their own files for easier modification/readability.

Not mentioned in any of the commits but I added a check to see if (neo)vim was compiled with python3, so that if it was compiled with it, it wouldn't break because it didn't have +python but +python3, since the python code should be py2 and py3 compatible.

PS: Should probably check if neovim is being used instead of vim with has('nvim') and passing it as an arg to the python scripts