Updated submodule.

Submodule src/main/xproc 7bf9f01..baca342:
  > Removed column Druckort from testimony table.
  > Documentation
  > Sigil links in testimony metadata
  > Druckort
  > Dokumenttyp => Beschreibung auch in Metadaten
  > Metadata fields re. date
  > Ignore some testimony metadata fields
  > Normalize characters in testimonies.
  > Updated bibliography