native win32 opengl client

[totaam]

This may help with testing and with things like #916, #917.

It shouldn't be too hard to make a simple win32 client using pywin32 + opengl.
Doing so would also help to ensure that the separation between the gtk client, ui client class and platform code is clean.

Here's some example code:

• glglue: wgl.py
• pywin32 openGLDemo.py

Things like the clipboard are due to be re-written anyway (#812), and sound is out of process already.
The keyboard support can't be too difficult either.

[totaam]

See also: #1569 python3 opengl client

[totaam]

The code is now much more modular: see #1569 comment:2.