use onWindowFocusChanged(bool) instead of onResume()/onPause()

we should use onWindowFocusChanged(bool) to detect if the app is currently
visitible to the user or not. because onPause()/onResume() leads to false
positives on some android versions (e.g. Kindle Fire). if you lock those
devices, while the app running, everything is fine (onPause() is handled
properly). but as soon as you wake up the device, and the lock screen gets
visible, the app is resumed and the music is played (onResume() is
called to early).

this is a) not the best behaviour and b) such games will be rejected on the
samsung app store. onWindowFocusChanged(bool) is, like onPause()/onResume(),
available since API level 1 and it should be safe to simply switch.
Linux: added project part for QtCreator.

Allows easily setup cocos2d on Linux in QtCreator IDE.
Enabled c++0x flag, use OpenAL audio backend by default.
issue #2305: use c++11 thread instead of pthread in CCTextureCache
issue #2305: tab -> 4 spaces
issue #2305: tab -> 4 spaces
Merge branch 'iss2305-replace-pthread' of https://github.com/minggo/cocos2d-x into minggo-iss2305-replace-pthread
issue #2305: use 4.7 toolchain to fix compiling errors
Using llvm 3.3 and android cxx-stl 4.7.
Updating bindings-generator.
Merge branch 'iss2305-replace-pthread' of https://github.com/minggo/cocos2d-x into minggo-iss2305-replace-pthread
[Travis CI] Removing space for before-install.sh.
clang+llvm-3.1 --> clang+llvm-3.3
Compilation errors in ScriptingCore.cpp fixes
issue #2322: Adding Property Sheet cocos2dx.props for sharing project configuration. Now it's only for linking libraries.
issue #2322: Macro CC_DLL take no effect now since we are using static library.
issue #2322: Action now is inherited from Object and Clonable now.
issue #2322: Fixing a warning in extensions/CCArmature/utils/CCDataReaderHelper.cpp.
closed #2322: Updating all win32 project configurations, improvement by using Multi-processor Compilation.
Merge pull request #2976 from dumganhar/iss2322-link-error

closed #2322: [Win32] Linking error when using multiply inheritance.