indexes the Document status (whether they're OA or not) - used for facets only
indexes the year bit of a date (used for facets)
Module handling any aspect of facetting (except for the layout which is done by the relevant Paginate module):
loads valid facets from configuration
loads selected facets (from UI, query params)
computes potential facetable values (from search results)
allows to be serialised/de-serialised
builds Xapian sub-queries (when facets are applied to the search)
allows local render_value method over-ride
simplification: assume dataobj is an eprint object
allows to switch from one dataset to another whilst indexing - this should only ever happen if called from the EPrints 'indexer' which caches the Xapian Index object
Refactored/enabled facets:
moved all computing of facets to a separate module Xapian/Search/Facets
adapted UI and Search plug-in to use that module
added missing phrases
Xapian CSS files - only used by Paginate/Facets for now