Support resizing PyNvim window

[viccuad]

I haven't been able to resize pynvim window, with neovim 0.1.2, python-client 0.1.2 and python-gui 0.1.1 (I haven't tried with neovim's master and python-client >= 0.1.3).

[bfredl]

looks like division issue. Please try master (which needs latest python-client)

[zsedem]

It does fixed for me using the master for this repo and up-to-date arch linux packages for dependencies