A single word finds the names and titles that contain it, `report` finds
Report.txt, on bleve as well as on OpenSearch, which so far only did it by
accident of its dynamic mapping. Modelled like SharePoint's NoWordBreaker:
a keyword field is one whole value unless the override switches that off,
which adds a search-only _words sibling next to _lowercase, analyzed into
lowercased words (a dot is a word boundary, no stemming). The base stays the
whole value for returning and aggregating, wildcards and whole values keep
using _lowercase. Quotes do not change the meaning, a phrase is a phrase
either way, and there is no exact-match operator yet.
Dominik Schmidt
6b07ea745c