Added Solr deduplication support.
- See https://vufind.org/wiki/deduplication
Improved error and debug logging for MultiBackend driver.
Improved logging of function parameters in exception backtrace.
Improved error and debug logging for Voyager drivers.
Relay record id to checkFunction() so that the backend can return configuration based on the record (e.g. MultiBackend driver can get config from proper backend).
Fixed error status and message reporting for restful request (leftover from VuFind 1).
Merge commit 'd9c8fa64cd7b7bc51f4ddd9d0d46ddd4dcf8dd29' into vufind-master
Switch sort option to GET rather than POST.
- Resolves VUFIND-947.
Added session database cleanup tools.
- Resolves VUFIND-948.
Minor tweaks to Finnish translation.
Merge pull request #79 from KDK-Alli/translation

Minor tweaks to Finnish translation.
Added cross-reference to config comments.
Updated language file.
- Thanks to Jorge Ramírez.
Updated Basque translation courtesy of Josu Moreno.
Updated German translation courtesy of Markus Fischer.
Avoid notices; resolves VUFIND-950.
View choice icons are now clickable.
Hotfix: IE 11 compatibility.
TODO: upgrade to newer official jsTree release; may require jQuery upgrade.
Updating version number for next release.
Improved compatibility with Apache 2.4.