Symphony: factor out LibraryFilter logic
Symphony: defer work to after filtering
Symphony: improve getSessionToken() comments
Symphony: implement LoggerAwareInterface
Symphony: support populating holdings_text_fields with MFHD
Merge pull request #189 from quartsize/master

Symphony driver MFHD support etc.
Fixed incorrect string.
Merge branch 'release-2.3'
Updated Dutch translations from Anneke Goovaerts.
Merge branch 'release-2.3'
Removed unnecessary strings.
Symphony: improve comments
Merge pull request #190 from quartsize/symphony

Just some more Symphony.php comment improvements