Removed PreferredInterfaceOrientationForPresentation()

Causes bugs with PresentViewController to be described in pull request
GamePad now throttles checking disconnected controllers.
Removed uses of extremely slow Enum.HasFlag() in GamePad.
GamePad now throws InvalidOperationException when called with a bad player index.
Removed excessive function call nesting in GamePad.
Fixed GamePadCapabilities.HasDPadRightButton which was incorrectly testing the left dpad button state.
Merge pull request #1936 from jonathanpeppers/develop

Removed PreferredInterfaceOrientationForPresentation() for iOS
Merge pull request #2000 from SickheadGames/xinput

GamePad XInput Performance
Merge branch 'develop' into stable_BtA