Issue18 homotopy

Merge branch to master to fix issue #18.
Note that PartialFourPortInterface.mo has many changes which are mostly corrections for the line endings.
All unit tests run fine. Minor differences in results have been noted in PIDHysteresisTimer and MixingVolumeMoistAir which are most likely due to a change in Dymola from 2014 to 2014 FD01.