more convenients for android developer when reading code with the cmake.

[jw20082009]

trafficstars

加入了cmake编译，方便安卓开发者在阅读代码时使用上快捷方式，脱离刀耕火种

[wysaid]

Merged into branch cmake, but it shows me some err below:

[jw20082009]

you need a ndk r14，maybe your ndk version is too high

[netherpyro]

root CmakeLists.txt should contain CMAKE_CXX_FLAGS with ${CMAKE_CXX_FLAGS} flag in it. Like this: set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -frtti -std=gnu++11 -D_CGE_USE_FFMPEG_ -DDEBUG -DANDROID_NDK -DCGE_TEXTURE_PREMULTIPLIED=1 -D__STDC_CONSTANT_MACROS -D_CGE_DISABLE_GLOBALCONTEXT_ -O3 -ffast-math -D_CGE_ONLY_FILTERS_")

[wysaid]

merged, but changed a lot.