Issue35

[ferrighi]

This PR closes #35 . It contains:

• update of the vocab tool, with extraction of platform and instrument information (short name, long name and wmo reference)
• the latest updated version of the vocabulary terms
• a modification of nc_to_mmd where given the platform attribute
  • it checks if the preferred name is provided either as string (short name) or in paranthesis (e.g. long name (short name)) and it populates long_name and resource through vocab.
  • it supports both single string and comma separated
  • it adds instrument using the same approach as for platforms

For now, the length of platform and instrument must be the same, since in MMD the instrument is a child of platform. This could be improved when other types of platforms/instrument are supported. Alternatively, the isHostedBy/hosts statements could be used from vocab to establish if one instrument can be linked to several platforms (in case of mismatching lengths).

[steingod]

What happens if a platform or instrument is not in the list? If this happens a separate error report or similar should be generated so we can update the controlled vocabularies over time. Same with instruments. As it is now it only reflects satellite remote sensing, but the MMD specification as such does not constrain it to such. It could be used to name a research vessel as well and these have less formal naming governance of lists than satellites. I would suggest to let more through with a possible warning list generated.