Add display support Proof Of Concept

[elgopher]

This PR is for experimentation with monitor support. The goal of it is to prototype new API and gather know-how needed to build production-grade API.

• Add API for getting information about monitors
• Open windows in fullscreen mode
• Set fullscreen/windowed on existing window
• Get and Set Window position

Some interesting findings:

• changing window size (going fullscreen) is asynchronous
• when resizing the window the size callback may not be called at all. Therefore method such as Resize must return an error after some timeout.
• current video mode on MacOS X cannot be used for openning fullscreen window (the resulting window has a different size)

[Nietworzy]

Good code @jacekolszak!