[Backend] Improve search result relevance algorithm

[galadhremmin]

The current search relevance algorithm uses 'nearness' to the search term. It's imperfect and it doesn't work particularly well for inflections. Also, multiple language responses are sometimes ordered in a manner that the most relevant results are pushed below the fold.

What can we do to improve the search result relevancy?

Code pointer:

Parf-Edhellen/src/app/Adapters/BookAdapter.php

Line 370 in 4b212d3

public static function calculateRating(\stdClass $gloss, string $word)