Add PyQt5 support

[rominf]

See my fork of pandas: https://github.com/rominf/pandas/blob/master/pandas/sandbox/qtpandas.py

[datalyze-solutions]

Hi, I don't have enougth time at the moment (there are so much presents waiting to be packed 😃 ). But I think I've time in january. Maybe you can folk the pandas-qt repo and try the PyQt5 support with it?

[rominf]

@datalyze-solutions, ОК, I'll think about that. I don't have time too :(

[dmopalmer]

I just submitted a pull request that supports all pythons (2.7 and 3.5), all interfaces (PySide, PyQt4, PyQt5).

It doesn't work perfectly. I am not a person who will make it work perfectly. It is an improvement.

[kaotika]

Many thanks for the extensive contribution. I will check and add it.