Merge people automatically

[ryscher]

When a new Person is created:

• search for existing people that match, using ORCID and emails
• if there are any matches, merge the new person into the old person:
  • if references have already been made from other objects to the new person, update those references to point to the old person
  • use values from the most recent person for all fields. But if any fields are missing in the new person, retain the values from the old person
  • retain old email addresses in the email array