fatcat should probably allow all roles, but only emphasize:
- author
- editor
- translator
- illustrator

possible additional (non-CSL) roles:
- chair

Crossref has the additional "chair" contributor_role: '"chair" should only be
used for conference proceedings to indicate a conference chair'.

All CSL Roles:
- author
- collection-editor
- composer
- container-author
- director
- editor
- editorial-director
- editortranslator
- illustrator
- interviewer
- original-author
- recipient
- reviewed-author
- translator

From: <http://docs.citationstyles.org/en/stable/specification.html#roles>