Add matrixinverter test

- fixes the matrix inversion test

[test] refresh test timings

Improve shifted qr solver

Merge branch 'master' of https://github.com/dune-community/dune-xt-la into try_to_fix_real_eigensolver

Pylicense update

Fix eigensolver for non-symmetric real matrices with real eigenvalues

it was missing the constuctor that takes a communicator object