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
Added MaxTextureSize to GraphicsDevice

In XNA Textures can be larger than the screen (though there is a
maximum size) while in OpenGL they can't. This property returns the max
allowed. (for Windows DirectX it uses the XNA values to help porting)
Revert "Added MaxTextureSize to GraphicsDevice"

This reverts commit 1d064c458491815b2d9b868c13e07df1e35ec425.
Merge remote-tracking branch 'upstream/develop' into develop
[MonoMac] SaveAs* Implementations for MonoMac
Added info for the source versions of assimp/assimp-net binaries.
Minimal importer. Geometry doesn't look quite right yet.
Filled in missing content type methods.
Bugfix: DirectX effect files used sampler states in wrong order.

Sampler info stores textureSlot and samplerSlot separately.
SamplerStateInfo._dirty is true per default to always create a sampler state.
Rebuilt stock effects.
Incremented MGFX version.
Bugfix: SamplerStateInfo._dirty must always be set when a property is changed.
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 pull request #1461 from DigitalRune/samplerfix

Bugfix: DirectX effect files used sampler states in wrong order.