Merge branch 'issue61_dymola2015' into issue65_synchBuildings
Added additional Type declaration.

These are needed for heat exchangers in Buildings library.
Improved documentation.
Removed unrequired assignment of species concentration.
Added pressure drop.

This is needed for te model to also work with incompressible media, such as used in the Buildings library.
Merge branch 'master' into issue65_synchBuildings
Removed import statements.
Removed import statements.
Merge branch 'issue65_synchBuildings' into issue45_benchmarks