HeatingSystem

This pull request handles the following:

remove unnecessary condition _standAlone_ in FreeFloatBuilding
add missing connector in Heating_Embedded_DHW_STS
add zero flow in heatPorts of heatingSystems to be compatible with building interface.
remove final for parameters of heatingSystem to avoid conflict in building interface.
rewrite VentilationSystems.None to extends VentilationSystem instead of VentilationSystem.Ideal
so that the None appear in the drop down menu.

I will merge it myself as this does not influence other models.