[atv2] - added substrate.h - needed for hooking methods and ivars at runtime
[atv2] - bump seatbelt unlock patch for patching ios6.1 binary
[atv2/packaging] - on postinst copy our app icon to /Applications/AppleTV.app/com.apple.frontrow.appliance.xbmc\@720p.png - needed for ios6
[atv2] - fix darwinutils - we can't rely on the class name XBMCAppliance because its now generated at runtime. This means the NSBundle functions on that class won't return our appliance
[atv2] - add a missing key to our atv2 - info.plist
[atv2] - forward declare BRWindow in iosscreenmanager
[atv2] - rewrite the XBMCAppliance and XBMCController for using obj-c runtime class definition and hooking. This is needed for supporting atv2 on ios6 (see the comments in the impl.)
Merge pull request #2268 from Memphiz/ios6

[atv2] - support for ios6

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