Simplified random Solr record retrieval.
Added support for ILS drivers interacting with non-Solr backends.
Reduced redundancy; added important missing fields.
More flexibility for request links (work in progress).
Add source to saved requests; cleaned up some quotes.
Implemented support for simple container-child record links using the hierarchy fields.
MultiBackend driver: Added second parameter to supportsMethod() calls, fixed some comments and tweaked variable names and debug messages.
MultiBackend: made getSourceFromParams more strict so that it doesn't try to get the source id from wrong fields and fixed the tests accordingly.
Merge commit '77b4c70cdd86c08159fce664ecd275c4df08d232' from vufind-org/master

Conflicts:
	module/VuFind/src/VuFind/View/Helper/Root/RecordLink.php
	themes/bootstrap3/templates/RecordDriver/SolrDefault/core.phtml
	themes/bootstrap3/templates/RecordDriver/SolrDefault/result-list.phtml