BackButton support for WP8
Added fake GamePad class
Implemented Game.Exit()
Merge branch 'orientation' of https://github.com/Nezz/MonoGame into wp8_backbutton_v2
Get BackPressed from page
Merge branch 'orientation' of https://github.com/Nezz/MonoGame into wp8_backbutton_V2
Updated template
Merge branch 'orientation' of https://github.com/Nezz/MonoGame into wp8_backbutton_V2
Merge branch 'orientation' of https://github.com/Nezz/MonoGame into wp8_backbutton_V2
ModelMeshPart.Effect now removes the old effect from the ModelMesh if no one else is using it.
Fixed mouse scroll wheel on WinDX desktop.
FindImporterByExtension() is no longer case sensitive.
Merge branch 'develop3d' of https://github.com/mono/MonoGame into wp8_backbutton_V2
Fixed case where a disposed texture is still in the TextureCollection.
XAudio2 creation can fail.
Improvements for Ouya GamePad

Adds support for disconnecting and reconnecting gamepads including the GamePadState.IsConnected property. Reconnected gamepads get the same player number that they previously had.

Added GamePad.GetState() override taking GamePadDeadZone.
Removed unnecessary garbage generation from Model.Draw

Problem: Model.Draw method was generating considerable amount of unnecessary garbage by allocating new bone transform matrices arrays with every call to the method.

Solution: New static field was introduced which replaces the role of bone transforms array. This array is static in order to save memory. We do not need separate instance for each Model because the transforms are set always directly before drawing the Model. At each Draw method call, the array is checked if it is null and is long enough hold transforms for Model with highest number of bones.
Fix to using Any() instead of Count().
Removed the Tests submodule.
[All platforms]: TextInputEventArgs class

Used for cross-platform use.
[WinDX]: include TextInputEventArgs.cs
[WinGL]: include TextInputEventArgs.cs