Add multizone air flow from Buildings
Add bechmarks package
Use Validation3Rooms as foundation for air bm

For #82
Add first implementation of SimpleZone

For #82
Define Medium at ports of simpleZone

For #82
Merge branch 'master' of https://github.com/iea-annex60/modelica-annex60 into issue82_airBenchmark
Update reference in TwoWayFlowElementBuoyancy
Add Outside Environment and Hallway model
Add first test of modular multizone testcase
Merge branch 'master' of https://github.com/iea-annex60/modelica-annex60 into issue82_airBenchmark
Make media in zones replaceable
Add first tests