LibXml2 replaced with Tinyxml2 and Mingw Compiler Support

Cocos now compiles with the Mingw and Mingw64 compiler on windows.
Platform folder only midified and it should act as normal for all other compilers
You must make your own makefile (I use cmake)

Could you guys merge please?

Now I have added tinyxml2 to both the windows 8 branch and the main gles20 branch to start the merge of the code base :)

Please Test