Add RenderTarget2D support

Fix Blender states
Merge remote-tracking branch 'upstream/develop' into develop

Conflicts:
	MonoGame.Framework/Graphics/RenderTarget2D.cs
Fix usings.
Merge remote-tracking branch 'upstream/develop' into develop

Conflicts:
	MonoGame.Framework/Graphics/RenderTarget2D.cs
Merge remote-tracking branch 'upstream/develop' into develop
Remove the RenderTarget2D.cs.orig file
Merge pull request #1427 from jalf/develop

Add RenderTarget2D support