Added image attaching for iOS Guide's Twitter

Added image attaching for iOS Guide's Twitter
Merge pull request #2718 from picobots/develop

Added image attaching for iOS Guide's Twitter
Avoiding loading content twice when a path is passed to us using different path separators or casing.
Fixed logic error.
Merge pull request #2722 from SickheadGames/CopyToOutput

Fixed logic error when copying a file to its output folder
Merge pull request #2721 from SickheadGames/FixPathSepAndCase

Fixed "Loading Content Twice" bug.
Fixed incorrect parsing of Number type.
Fixed cases of int.Parse() and float.Parse() to use the invariant culture.
Added a comment to clarify things.
Merge pull request #2724 from SickheadGames/mgfxculture

MGFX Fixes
Fixed possible ArgumentNullException in ContentTypeReaderManager.

ContentTypeReader.TargetType can be null, e.g. for ExternalReferenceReader.
Merge pull request #2725 from DigitalRune/contentreader

Fixed possible ArgumentNullException in ContentTypeReaderManager.
Added missing texture reload for DirectX
Removed non-WP implementation as it isn't needed
Changed iOS Twitter API to use UIImage

Changed iOS Twitter API to use UIImage instead of string
Fixed iOS Guide crash bug

Fixed the bug where using any GamerServices.Guide functionality on iOS
caused the game to crash
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