Pull request #791: CAS-14308 (CLONE of CAS-12844 for Release/6.6.1)
Merge in CASA/casa6 from CAS-14308 to release/6.6.1
* commit '6d00df2ac3db17d0c04d5f7274bf7e1d28dcbded': CAS-12844: check existence of keyword 'QuantumUnits' in PRESSURE table CAS-12844: modified treatment of the pressure valiable CAS-12844: fixed a bug CAS-12844: modified to take the pressure unit and an elevation of antenna from TB