Added QtCreator project for Linux and Windows (MinGW)

Tested on
1. Ubuntu 13.10, 64-bit, clang compiler
2. Ubuntu 13.10, 64-bit, GCC compiler
3. Windows XP, 32-bit, MinGW compiler
4. Windows 7, 64-bit, MinGW 32-bit compiler

There're no Qt5 port yet, but I'm going to add it later. Current progress is in [1], TODOs are in that commit message. Probably I should make refactoring on SimpleAudioEngine before publishing Qt5 port, because in Qt5 audio can be decoded only asynchroniously so it's better to move whole SimpleAudioEngine into separate thread for all platforms.

P.S. In game published to GooglePlay we have rare fatal Java exceptions due to non thread-safe SimpleAudioEngine in cocos2dx 2.1.4, so probably refactoring SimpleAudioEngine will be useful for Android too.

[1] https://github.com/sergey-shambir/cocos2d-x/commit/be7beb8d765dc03a1f5aa781e7b6a5f32f9a7e32