SDKBOX GPG testbed for nmpe 27.0

SDKBOX Google Play Games testbed for nmpe (network multi-player engine on C++), the version implemented on Cocos2d-x platform.

With this demo you can:
* Choose image from gallery;
* Take image from camera;

then:
* Create/Join Google Play game;

then:
* Send image to all participants=players in unreliable mode;
* Deliver image to all;
* Deliver image to all by small parts;
* Cancel your image sending;

* Switch to short messages (finger move) unreliable sending mode; (fastest, not safe)
* Switch to short messages synchronized delivering mode;

* Hide menu to tap some participant screen to zoom on it to watch unreliable sending and receiving speed;


In real GP multiplayer game you may send your game data instead of the image.