Pull request #73: Feature/VECTO-1453 battery time dependent internal resistance

Merge in VECTO/vecto-dev from VECTO/mq_vecto-dev:feature/VECTO-1453-battery-time-dependent-internal-resistance to develop

* commit '381693d7':
  adding missing file to documentation
  fix some testcases, hybrid stragety: calc aux energy for aux connected to REESS (approx.)
  bugfixes after extending battery to batterysystem
  update battery state in test powertrain
  implementing time-dependent internal resistance