[Toolkit.Game] Fix issue #363. Perform a ClearState before a new BeginDraw to ensure that there is no unstable d3d11 device states. Toolkit samples should work on Nokia handset
[Toolkit.Graphics] Allow to specify the DepthFormat a constructor time with a RenderTargetGraphicsPresenter
[Toolkit.Graphics] Use readonly on fields that should not be modified
[Samples] Hide SystemTray on all WP8 toolkit samples
[SharpDX] Update some internal usage of Dictionary<IntPtr,XXX> to use an IEqualityComparer<IntPtr> in order to avoid boxing/gc
[Toolkit.Graphics] Fix spritebatch GC allocs using Dictionary<IntPtr,...> use Dictionary<ShaderResourceView, ...> instead. Also calculate correct width/height per ShaderResourceView
[Samples] Remove all old sample.csproj