Revert 65355ba..206d9b9

This rolls back to commit 65355ba6c796d5b392daec44f3346e343347a369.
Merged files from master
Merge from Annex60:issue95-2_nominal

This change primarily avoids warnings about alias sets with different
nominal values in OpenModelica.
It also contains some reformulations that are needed for OpenModelica.
Removed pW_TDewPoi_amb.mo which is no longer used
Removed assignment of nominal value
Removed reference to base class.