Pull request #72: Feature/VECTO-1452 update pev e2 shift strategy

Merge in VECTO/vecto-dev from VECTO/mq_vecto-dev:feature/VECTO-1452-update-pev-e2-shift-strategy to develop

* commit '93ab1617':
  make min-speed for downshift polygon a parameter
  allow reading pev shift parameters from file
  finetuning PEV shift strategy
  refactoring PEV shift strategy: simplify required methods, prohibit eff-gearshift when at max recuperation, prevent gearshift on drive-off (until target speed reached, em-speed above n_P80low, or operating point at full-load)
  implementing first idea of shift polygons for PEV