Merge pull request #178 from lbl-srg/openmodelica

Merge changes for OpenModelica
Cleaned up code formatting.
Removed unrequired model MixingVolumeDryAir
Revised example models for MixingVolumes.
Added start value for hOut to avoid a warning in OpenModelica.
Removed base class Buildings.Fluid.MixingVolumes.BaseClasses.PartialMixingVolumeWaterPort.