start work on goal 2: identify and consolidate re-used and re-usable metadata elements

[atn38]

goal 2 of this project is to help people import their EML corpus into a relational database system. the output will likely work best with LTER-core-metabase, but ultimately it's the user choice. to that end, re-used metadata elements need to be identified and consolidated into lookup tables for import into database later.

we will need to identify:

• identical re-use e.g. people whose name across EML files are consistent.
• close but not identical re-use e.g. the same person whose name differ a bit across EML files. Look into OpenRefine and taxonomyCleanr for possible matching solutions.

in these EML elements:

• missing codes and categorical codes
• contributing parties: creator, associated parties, metadata providers, contact, and their ID
• geocoverage or sites
• keywords and keyword thesauri
• protocols
• taxa and taxa providers
• publications
• annotations
• boilerplate elements: project, project personnel, license, funding info, etc

we will need to sort some of those into different priorities