Merge pull request #50 in VECTO/vecto-sim from...

Merge pull request #50 in VECTO/vecto-sim from ~EMQUARIMA/vecto-sim:feature/VECTO-94-implement-vectosimulationmodel-for to develop

* commit 'f9e43294':
  tests for AxleGear are green
  engine test load jump
  adding test for axlegear module
  move unary minus operator to SIBase class
  testcases for axle gear work (values within range of given map, no extrapolation)
  adding testcases for interpolating power loss of axle gear
  reading gearboxdata, first testcase
  refactoring gearboxdata - separate property for axle gear
  adding tests for gearbox data, transmission loss map, shift polygons
  parsing gearbox data works (including shift polygons and transmission loss maps), tests TBD.