Added missing texture reload for DirectX
Removed non-WP implementation as it isn't needed
Remove unused usings (Targeting System.Linq)
Replace Linq usages with non-linq implementations.
Remove Linq usage in TouchCollection, don't allow null touches to be provided (matches XNA on WP7), provide our own enumerator implementation (matches XNA)

http://msdn.microsoft.com/en-us/library/microsoft.xna.framework.input.touch.touchcollection.getenumerator.aspx
Merge pull request #2735 from danzel/tidy-linq

Tidy up unnecessary Linq usages
Fixed volume on WP8
Ensure struct enumerator on TouchCollection
Merge pull request #2737 from danzel/touchcollection-enumerator

Ensure struct enumerator on TouchCollection
Merge pull request #2736 from Nezz/wpvolume

Fixed music volume on WP8
Merge pull request #2733 from picobots/develop

Changed iOS Twitter API to use UIImage
Merge pull request #2731 from Nezz/directxtexturereload

Added missing texture reload for DirectX
Missing : in ToString.
Implement CurrentDisplayMode for Windows directx.

Fixes #2619
Implement SupportedDisplayModes for DirectX
Merge pull request #2738 from danzel/current-display-mode

GraphicsAdapter.CurrentDisplayMode for windows directx
Merge pull request #2739 from danzel/supported-display-modes

Implement SupportedDisplayModes for DirectX
Create pipeline.md
Update config.xml

Linked the new pipeline docs.
Initial pass at adding MGFX processing tests.