adding custom dymola commands

[Mathadon]

It would be nice if we could add Dymola commands prior to running the unit tests, for instance I need Advanced.CompileWith64=True since only 64 bit binaries are available for the software that I use and therefore the compiler should use 64 bit.

I put it in setup.mos for now, but it would be a nice feature to have this option in Buildingspy.

Another example, that I cannot fix with setup.mos, is that for my own library I'd like to generate reference results with Evaluate=true.

[mwetter]

It would be fine to add a command to `BuildingsPy that allows setting commands before the actual tests start, something like

>>> import buildingspy.development.regressiontest as r
>>> r = r.Tester()
>>> r.addPreProcessingStatement("Advanced.PedanticModelica = true;")
>>> r.run() 

[MassimoCimmino]

@mwetter, @Mathadon : Is this issue still relevant?

I needed this functionality to run some tests that require to load a library outside of the tested library.

I added the functionality here : 6508951.

[Mathadon]

I think it's still useful!