python pybind11

 for run https://github.com/ilastik/marching_cubes, we need to install pybind11
 alternative to test https://github.com/pmneila/PyMCubes

# prerequisites 
apt-get install cmake
pip3 install pytest

# Clone and build
git clone https://github.com/pybind/pybind11.git 
cd pybind11 
mkdir build 
cd build 
cmake .. 
sudo make install