Since the main display_name field ngrams words up to 15 characters,
anything to and under that will already be indexed - the fullword field
(which we have for words longer than 15 characters) needs to index only
words longer than that.
This fixes searching for "Machiavellianism", 16 chars ("Machiavellianis", 15 chars, worked previously).
Does not (seem to!) break anything, but requires a re-indexing of ES.