Rename SwapChainBackgroundPanel

References to SwapChainBackgroundPanel are currently named
'SwapChainPanel' (and sometimes 'swapPanel').

DX11.2/Win8.1 introduces a new UIElement,  'SwapChainPanel'.
http://msdn.microsoft.com/en-us/library/windows/apps/bg182880.aspx#three

I renamed all SwapChainBackgroundPanel because having then referred as
swapChainPanel could be confusing in the near future.

Arguments become -> 'swapChainBackgroundPanel'
Properties become -> 'SwapChainBackgroundPanel {get;set;}'
fields become -> '_swapChainBackgroundPanel'
Merge remote-tracking branch 'upstream/develop' into tnc_Rename_SwapChainBackgroundPanel
Fix WindowsGL project template : use the right Program Files folder and fix an issue with the resolving of assembly references finding the WindowsPhone ones before the Windows ones (error was MessageFilterHook type not found when launching a new WindowsGL project).
Fix assembly references for all project templates that were using MSBuildExtensionsPath instead of MSBuildProgramFiles32.
Merge remote-tracking branch 'upstream/develop' into tnc_Rename_SwapChainBackgroundPanel
Added Right and Left Orientation to template
Merge remote-tracking branch 'upstream/develop' into tnc_Rename_SwapChainBackgroundPanel
Fixed Mouse Button State Issues

Buttons would cancel each others ButtonState.Pressed  out, as well
rotating the mousewheel would cancel all ButtonState.Pressed
Merge remote-tracking branch 'upstream/develop' into tnc_Rename_SwapChainBackgroundPanel
Update XamlGame.cs
Merge remote-tracking branch 'upstream/develop' into tnc_Rename_SwapChainBackgroundPanel
Merge remote-tracking branch 'upstream/develop' into tnc_Rename_SwapChainBackgroundPanel
update recent changes
update changes
-update changes
Merge remote-tracking branch 'upstream/develop' into tnc_Rename_SwapChainBackgroundPanel
Merge remote-tracking branch 'upstream/develop' into tnc_Rename_SwapChainBackgroundPanel
Video support for Windows 8 Store apps.
Add support for loading indexed image files into a texture through Texture2D.FromStream.
Fix bug where GraphicsDevice.Clear() always cleared stencil and depth buffers.

This was a consequence of moving platform-specific code that prior to
eeafc23378861d1401ebdba417431b4e850e8abf only ran for the single-parameter
form of Clear() into a PlatformClear() method used by all forms of Clear().

This change splits it out again.