[pvr] fix unnecessary creation of new CPVRChannel instances
[builtin] fix activatewindow if directory path differs

After #5081 the built-in "activatewindow" does not work if you stay for example in the video window and you want to activate the same window with a different path.
This fixes the issue by comparing the directory path of the current active window with the given directory path of activatewindow.
DVDInputStreamTV/DVDInputStreamFile: Don't set EOF in case of error to give player a chance to retry read.
[vfs] PVRFile::Read(): do not return negative values other than "-1"
[ios] - support iphone6plus screensize which uses screenScale 3 and add
support for iPhone6 screen aswell
[ios] - add launch images for ip6 and ip6+ for enabling the new resolutions
[ios/vtb] - remove the video render scale down / clamp for all retina devices which have enought power to render unscaled
[ios] - add support for iPad Air 2 and iPad mini 3
[ios] - bump gas-preprocessor
[ios] - support Xcode 6.x and iOS 8 SDK

- use clang as default compiler for newer SDKs
- fakeroot: ignore interposing openat()
[ios] - fix libssh build with Xcode 6
[ios] - fix pil build with Xcode 6
[ios] - libRTV fix build for Xcode 6
ios] - fix libmpeg2 build error by making it even more PIC (also the real fix for the xcode5 build issue earlier)
[ios/atv2] - adapt readme - we support Xcode 6.0.1 against iOS 8 SDK
dxva: fix memory leak caused by additional ref on video surfaces
[pvr] bump add-ons
[pvr] fix call to base class GetContextButtons() to re-add favorite entry
[rebrand] - fixed some labels from strings.po files
[osx] - adapt readme for compatibility with Xcode 6.1 with OSX SDK 10.10 under Yosemite