[!790] Feature/add python bindings

Merge branch 'feature/addPythonBindings' into 'master'

ref:core/dune-common\> As discussed at the developer meeting (in 2018) the
Python bindings are being moved from dune-python into the core modules.
Corresponding merge requests are open in
`dune-geometry, dune-grid, dune-istl, dune-alugrid, dune-spgrid, dune-polygongrid`
and in dune-fem,dune-fem-dg,dune-vem

I want to merge this quickly because rebasing all the merge request will get
more involved the longer I wait. @all so if there are any comments please let
me know

See merge request [!790]

  [!790]: gitlab.dune-project.org/core/dune-common/merge_requests/790


Closes #28