BibDocFile: bibdocmoreinfo query typo fix

* Fixes a typo in the SQL query of BibDoc.fix() related
  to the bibdocmoreinfo table.
  (closes #1706)

* In the same method, fixes how version is split
  from filenames, when crawling the filesystem,
  to take into account the introduction of subformats.

Co-authored-by: Samuele Kaplun <samuele.kaplun@cern.ch>
BibIndex: common words in virtual index

* Fixes indexing of a virtual index
  in case of removing/modifying a term which is
  in more than one dependent index.  (closes #1653)

Signed-off-by: Grzegorz Szpura <grzegorz.szpura@cern.ch>
Tested-by: Tibor Simko <tibor.simko@cern.ch>
WebStat: ingestion health monitor fix

* Removes hardcoded set of indexes to monitor. Takes
  names of indexes to monitor from database instead.
  (closes #1631)

Signed-off-by: Grzegorz Szpura <grzegorz.szpura@cern.ch>
Tested-by: Tibor Simko <tibor.simko@cern.ch>
BibIndex: separate class for virtual index

* Introduces separate class for virtual index.

* Virtual indexes now communicate with their dependent
  indexes through queue table. This approach solves
  problem of parallel execution for virtual index.
  (closes #1661)

* Corresponding fixes for bibindex admin interface and
  regression tests.

Signed-off-by: Grzegorz Szpura <grzegorz.szpura@cern.ch>
Tested-by: Tibor Simko <tibor.simko@cern.ch>
BibIndex: new abstract class for indexes

* Introduces new abstract class for inheriting
  for virtual and regular indexes.

* Cleans WordTable argument list.

* Removes unused imports from bibindex_engine file.

Signed-off-by: Grzegorz Szpura <grzegorz.szpura@cern.ch>
Tested-by: Tibor Simko <tibor.simko@cern.ch>
BibIndex: new pattern for tokenizer inheritance

* Introduces abstract BibIndexRecJsonTokenizer
  and BibIndexMultiFieldTokenizer.

* Changes inheritance tree for other tokenizers.

* Changes mechanism of selecting a tokenizer inside WordTable.
  (closes #1704)

* Fixes admin interface to hide abstract tokenizers from
  users.

Signed-off-by: Grzegorz Szpura <grzegorz.szpura@cern.ch>
Tested-by: Tibor Simko <tibor.simko@cern.ch>
BibIndex: documentation for virtual indexes

* Adds initial documentation for the virtual index facility.

Signed-off-by: Tibor Simko <tibor.simko@cern.ch>