WIP fixes to FontDescriptionProcessor.
Merge branch 'FontProcessor' of https://github.com/SickheadGames/MonoGame into FontProcessor
Merge branch 'develop3d' into FontProcessor

Conflicts:
	MonoGame.Framework.Content.Pipeline/MonoGame.Framework.Content.Pipeline.Windows.csproj
Merge branch 'develop3d' into FontProcessor
Merge branch 'FontProcessor' of https://github.com/SickheadGames/MonoGame into FontProcessor
Prevent the importer from adding duplicate characters.
Removed outdated comments
Workaround that allows generic readers to be looked up.
First functional SpriteFontDescription .xnb written.
Merge branch 'FontProcessor' of https://github.com/SickheadGames/MonoGame into FontProcessor
Merge branch 'develop3d' into FontProcessor
Removed unnecessary #usings.
Miscommit. Removed unused helper class.
Removed unnecessary comment for testing.
Bounding volumes improvements

- Simplified BoundingFrustum implementation
- Added implementation for BoudingFrustum.Intersects(BoundingSphere)
Fix iOS build

- missing using statement
Improve render states support for OpenGL / OpenGLES
Fix SamplerState (OpenGL)

- Fixed texture target typo
- Added proper boundary check for MaxAnisotropy
Fix EffectParameter.SetValue(Texture)

- EffectParameter.SetValue(Texture) shouldn't throw an exception when passing null (XNA 4.0 doesn't)
Fix WindowsGL build