Add known types from GLODAP

[karlmsmith]

Add more known data types such as those used by GLODAP.
This includes typical and extreme limits for bounds checking, but this goes further, requiring standard metadata information.
Thus SocatMetadata needs to be updated with classes for those data types and instruments associated with those data types.
(This was the one open issue under what was originally the NOAA-PMEL/SDIMetadata repository.)