Merge branch 'chayward/refextract-authextract'

* chayward/refextract-authextract:
  refextract: use appropriate marc tags
  refextract: improve affiliated author search
  refextract: improve realign numeration
  refextract: include author choice heuristics
  refextract: improve author/affiliation extraction
  refextract: attempt at integrating giva
  refextract: removes leading whitespace characters
  refextract: author replication for IBIDs
  refextract: corrects some issues raised by Annette
  refextract: improved author recognition
  refextract: further changes
  refextract: author identification
  refextract: improvements
  refextract: adds DOI recognition functionality
  refextract: basic framework for author extraction