BibDocFile: textification with OCR fix

• Textification with OCR is based on a pattern matching against the the docname of a BibDoc. This has become a property between a record and a BibDoc. The code is here updated, thus allowing again textification to work. (fixes #1676)

Signed-off-by: Samuele Kaplun <samuele.kaplun@cern.ch>