Added MaxTextureSize to GraphicsDevice

In XNA Textures can be larger than the screen (though there is a
maximum size) while in OpenGL they can't. This property returns the max
allowed. (for Windows DirectX it uses the XNA values to help porting)
Revert "Added MaxTextureSize to GraphicsDevice"

This reverts commit 1d064c458491815b2d9b868c13e07df1e35ec425.
Merge remote-tracking branch 'upstream/develop' into develop
[MonoMac] SaveAs* Implementations for MonoMac
Merge remote-tracking branch 'upstream/develop' into develop
Merge pull request #1429 from SamuelEnglard/develop

[MonoMac] SaveAs* Implementations for MonoMac, this is just new code, with no changes to existing code. This is safe to merge as-is without a functional test.