Adds group support to the core search API and the Solr search engine.
This allows for:
* User searching by group (in the API only, no interface yet)
* Automatically restrict search results by group (in some cases like
separate-groups forums)
This new API returns a list of contexts for each search area. This
allows the areas to be reindexed in a sensible order (roughly
speaking, newest first) and also allows this to be controlled by
each area.
An implementation in the forum module means that forums are ordered
by the date of the most recent discussion, so that active forums
will be reindexed early even if they were created a long time ago.
The search area API now includes a new function get_document_recordset
which should be implemented in preference to the older
get_recordset_by_timestamp. (It's also possible to implement both in
plugin search areas which need to work against older Moodle versions.)
Existing search areas without the new function will continue to work as
before (obviously without the new functionality).
Increase the scope of the files that are detected and
indexed by Moodle's Global Search. This includes intro
and content areas of search areas. The use case here is
in a description for an activity there is a file added
that contains more information about the activity.
It would an advantage to be able to search this content
as well. It would also allow search engine plugins to be
able to index non text files such as images.
