Adds new API support within search engines for optional methods to
delete data for courses and contexts, and implements this for the
two core search plugins (simpledb and solr).
The new API is automatically called when courses or contexts are
deleted. When a whole course is deleted, it only sends the course
delete rather than sending 1,000 separate context deletions as
each activity/block is deleted.
If you have Global Search set up on a site without file
indexing enabled, then at a later date you enable file indexing
files associated with existing objects are not added.
The only way to have files for existing objects indexed is to
run a reindex of all content.
This patches updates the file indexing language string in the
solr search settings of Global Search to make this clear
to the site administrator.
Also removing is_server_ready call from execute_query as in production
workflows search is done through \core_search\manager::search and
\core_search\manager::instance already checks is_server_ready. In
testing environment setUp functions should check that the server is
ready before performing other actions.
Expand the Solr engine to use the built in (to Solr) Tika
file indexing engine. Files are shipped off for indexing with
curl. Each file must have it's own document. So grouping is
used to keep files and Moodle docs associated.
