Using python 2 or python 3

[rtrepos]

On linux systems (at least ubuntu) one can use either python 2.7 or 3.x.
Pyvle relies on boost.python. This lib comes with 2 versions (for python 2 and 3) of the .so but I can find only one include version (/usr/include/boost/python.hpp) which is for python 2.7 version. I did not succeed in compiling pyvle for python 3.x.
Maybe something is missing ?

Could other alternatives (hpp only) be usefull such as pybind11 or SWIG ?

[rtrepos]

This is related to #12