v1.4.0

This contributes python bindings. Since this is a template C++ library, the python bindings have to be compiled at a later point in time, when the types are known. Therefore, we don't ship the bindings directly but rather add a convenience function that allows binding the types once the template arguments are known.

When pybind is available and BUILD_TEST=TRUE, a python module is built that allows running unit tests (almost) equivalent to the C++ ones.

#minor