调整重力方向适用平板；重力改变时，激活睡眠刚体。
#	modified:   Classes/Box2dLayer.cpp
#	modified:   proj.android/libs/armeabi/libgame.so
响应ESC或者BACK键
#	modified:   Classes/AppDelegate.cpp
#	modified:   Classes/BaseLayer.cpp
#	modified:   Classes/BaseLayer.h
#	modified:   Classes/Box2dLayer.cpp
#	modified:   proj.android/libs/armeabi/libgame.so