Add StoichiometricCoefficient next to StoichiometricNumber (modelica#…

…4105)

* Add StoichiometricCoefficient next to StoichiometricNumber

* Set min=0

Co-authored-by: Hans Olsson <HansOlsson@users.noreply.github.com>

* Minor cleanup

* Remove `min=0` for StoichiometricCoefficient type in Units.mo

* Introduce `min=0` for StoichiometricCoefficient in Units.mo

---------

Co-authored-by: Hans Olsson <HansOlsson@users.noreply.github.com>
Co-authored-by: arunkumar-narasimhan <124154466+arunkumar-narasimhan@users.noreply.github.com>

Modelica/Units.mo

@@ -785,6 +785,9 @@ end UsersGuide;
         min=0);
     type StoichiometricNumber = Real (final quantity="StoichiometricNumber",
           final unit="1");
+    type StoichiometricCoefficient = Real (final quantity="StoichiometricCoefficient",
+          final unit="1",
+          min=0);
     type Affinity = Real (final quantity="Affinity", final unit="J/mol");
     type MassOfMolecule = Real (final quantity="Mass", final unit="kg");
     type ElectricDipoleMomentOfMolecule = Real (final quantity=