Optimize .XAP size

This prevent the .XML documentation files (MonoGame.Framework.xml,
SharpDX.xml, etc) to get copied into the .XAP file. Those are text files
and compress well in the xap but take significant space once the app is
deployed.

I created two projects, Game1 (old template) & Game2 (new template),
build with ARM/Release  and deploy to the phone.

In the /Bin directory:
Game1_Release_ARM.xap 1163 KB
Game2_Release_ARM.xap  572 KB

On the phone (Settings/Phone Storage/Apps)
Game1_Release_ARM.xap 14,15 MB
Game2_Release_ARM.xap  7,20 MB
Use AfterResolveReferences
Changed ToLower/ToUpper to culture-insensitive ToLowerInvariant/ToUpperInvariant.
Merge pull request #2857 from Andreyul/ToLower_ToUpper

Changed ToLower/ToUpper to culture-insensitive ToLowerInvariant/ToUpperInvariant
OpenGL SamplerState had null GraphicsDevice
The GraphicsDevice had never been set in the OpenGL version of SamplerState. This PR sets it and checks for the SamplerState being used on the same GraphicsDevice as it was first used, similar to the DirectX version.
Merge pull request #2858 from KonajuGames/samplerstate-opengl-graphicsdevice

OpenGL SamplerState had null GraphicsDevice
Merge pull request #2840 from nkast/tnc_optimizeXapSize

[WP8] Optimize .XAP size