Removed Annex60.Utilities.Psychrometrics.Functions.BaseClasses.pW_TDewPoi_amb

Extending from
Annex60.Utilities.Psychrometrics.Functions.BaseClasses.pW_TDewPoi_amb
caused OpenModelica to fail as it could not find the input argument T
Reimplemented saturationPressure for OpenModelica.

This fixes the problem in OpenModelica which caused
Annex60.Utilities.Psychrometrics.Functions.Examples.X_pSatpphi
to never return.
Set nominal values.

Changed assignment of nominal value to avoid in OpenModelica the warning
alias set with different nominal values.
This is for #95.
Fixed unit error.
Added Tolerance.

This is needed for OpenModelica to have high enough a precision to pass
the assert statements.
Removed reference to base class
Updated reference results for #95

Small changes due to a change in the nominal attribute.
Set start value

This is for #95 to avoid alias set with several free start values in OpenModelica
Changed medium propagation to be final.
Merge pull request #96 from iea-annex60/issue95-2_nominal

Issue95 2 nominal