[atv2] - forward declare BRWindow in iosscreenmanager
[atv2] - added substrate.h - needed for hooking methods at runtime
[atv2] - fix darwinutils - we can't rely on the class name "XBMCAppliance" anymore - instead detect xbmc@atv2 by the bundle identifier "com.apple.frontrow.appliance.xbmc"
[atv2/packaging] - on postinst copy our app icon to /Applications/AppleTV.app/com.apple.frontrow.appliance.xbmc\@720p.png - needed for ios6
[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.)