Adding core base files for raspberry Pi

- libtess2 is linked as a share library
- in the documentation I put how to switch the cmake version to avoid compiling cmake-3 on the rpi
- Pan gesture with mouse + Pan and Zoom with keyboard 
If you mean adding this to the cmake yes! We could `set(CMAKE_CXX_COMPILER /usr/bin/g++-4.7)` I think. And then we just need usr to install g++-4.7.