RefExtract: improved book search

* Improves book search: looks for books in misc text.

Reviewed-by: Alessio Deiana <alessio.deiana@cern.ch>
Tested-by: Tibor Simko <tibor.simko@cern.ch>
RefExtract: refactored book handling

* Refactoring of book search.

Signed-off-by: Alessio Deiana <alessio.deiana@cern.ch>
Tested-by: Tibor Simko <tibor.simko@cern.ch>