For testing, added code that does not work in OpenModelica.
Reverted debug changes of Media.
Applied patch from Adrian Pop.

This allows simulation of the example of the volume flow rate sensor with OpenModelica.
Corrected various syntax errors that were detected by OpenModelica.
Corrected various syntax errors that were detected by OpenModelica.
Added time in print statement as OpenModelica does not output the time when the assert is triggered.