Direct3D 11 Overlay support, additional Direct3D 9 support, heavy code cleanup

This PR is obsoleting the other two open DX11 PRs
* #28 
* #62 

It adds overlay support for Direct3D 11.
This has been verified in Crysis 2 (main menu).
Additionally, as verified with a self compiled SimpleSample.exe from the DirectX SDK using Direct3D 9 - the direct3d 9 overlay now displays in more cases as well.

It adds the fx11 (Effects 11) library into overlay/effects11.
A qmake project file has been added to allow compilation of it as a dependency. On building the mumble_ol.dll (overlay) it is added as a static library, thus no additional dll is necessary.

Fx11 is MS-PL licensed. MS-PL is incompatible to the GPL.
As such, to be able to distribute the overlay dll, we will have to distribute our windows binaries no longer as GPL but under our more liberal license.
This is subject to another PR.

A build has been tested to not break stuff with
* D3D examples (SimpleSample.exe for 9, 10, 11)
* Smite
* LoL
* Crysis 2
* Dota 2
* Awesomenauts
* Wolfenstein: Enemy Territory (OpenGL)