[Info] Multimonitor support on Windows

[maandree]

I am working on fake Windows library headers so that
gamma-w32gdi can be tested on Linux. I will probably
make it translate into RandR calls.

While reading about the functions used in gamma-w32gdi
I came across two documenation pages that look sufficient
to implement multimonitor support:

http://msdn.microsoft.com/en-us/library/windows/desktop/dd183490(v=vs.85).aspx
http://msdn.microsoft.com/en-us/library/windows/desktop/dd162609(v=vs.85).aspx

[jonls]

This is still a valid feature request, no?

[maandree]

Implemented in #61, however it has not been test on Windows.