Add function for handling synonyms

[cboettig]

• Create synonyms table for all databases that provide them:
  • [x] COL
  • [x] NCBI
  • [x] ITIS
  • [x] FB (done in rfishbase synonyms() / validate_names(), needs porting here)
  • ....

Join all synonyms tables together for a more comprehensive list(?). Will require de-duplication.

Create a function that will query the name against synonym list and return the correct match. Note: unlike a generic 'fuzzy match' or 'spell check', most synonym tables provide specific matches to accepted IDs/names. This is nice as it permits automation where we can auto-correct names without having to request user input, but a fuzzy-match behavior might be a useful further addition.

[cboettig]

Done, but will be rolled into #12