Rework dispose list
Try to fix issue #910
The dispose list is now static in GraphicsDevice, so adding to the list no longer requires an instance of GraphicsDevice. This removes use of a WeakReference in a finalizer.
Don't wrap AddDisposeAction in if (disposing).
Merge branch 'develop3d' of https://github.com/mono/MonoGame into dispose
GraphicsResource
* Fix incorrect comment and spelling error.
* Set graphicsDevice member to null in Dispose(bool) to release reference.
Fixes #899
Fixes #923 (assuming we set the MediaState correclty)
Fixes strange behaviour of Windows 8 trial
Rewordked messagebox for correct behaviour
Moved the IsVisible sets to the delegates so the Guide won't get stuck if the EndShow functions are not called
Removed using.
Added neutral resource attribute.
First pass at working WP8 platform.
Better state cleanup between frames.
Updating libs submodule reference to head.
Removed AnyCPU from Windows Phone project.
Fixed some warnings.
Went ahead and made initialization behave more like WinRT.
Fixed gamepad not working for PlayerIndex.Two and beyond.

Added another model of 3rd party Xbox compatible controller
Added support for single int parameters in MGFX (in a somewhat dirty way)
Fixed BeginOpenContainer->EndOpenContainer not working properly
Fixed root path of StorageContainer not being inside of SavedGames/ContainerName
For some reason an object cannot be a DrawingSurfaceBackgroundContentProviderNativeBase and a IDrawingSurfaceManipulationHandler.
Made some methods static.
Fixed case where viewport was not being set under WP8.
Windows 8 projects now define WINDOWS_STOREAPP (aka "Metro" style apps).
Replaced cases of #if WINRT && !WINDOWS_PHONE with #if WINDOWS_STOREAPP.