Pull request #69: Feature/VECTO-1447 allow modular batteries

Merge in VECTO/vecto-dev from VECTO/mq_vecto-dev:feature/VECTO-1447-allow-modular-batteries to develop

* commit 'ea4bf2d4':
  limiting e-motor voltage levels to min/max available voltage levels
  adding integration testcases for multiple batteries, adapting hybrid strategy to take over state of battery system to testpowertrain, write information for all batteries to .vmod, batterysystem: fix writing .vmod SoC of whole system
  saving and loading battery system works, write modal results for batterysystem (total/average of all batteries / battery strings)
  implementation of modular battery system