Search optimisations

[rosemcc]

Description

This PR provides a couple of optimisations for search:

1. Boosting titles - if a search query is found in the title of an entry, then that result's score is boosted x2
2. Phrase queries (where a user is looking for an exact phrase by using quotation marks around the query) are fixed

Solution

1. Boosting titles: added a function which wraps around the existing Elasticsearch query which takes the output of the query, then applies a function to increase the weighting of results that contain the search query in the title field. Results with matches in the title will now show further up the list of search results.
2. Phrase queries: Fixed a bug where phrase queries (and other query operators) and fuzziness operators were interfering with each other. Now, if a search query contains any of these operators: '+', '|', '-', '*', '"', '(', ')', the fuzziness operator will not be used which will improve the search results.

Screenshots

N/A

Testing

No new tests have been added

Have the changes been checked in the following browsers?

N/A

[Trombach]

Looks good. Only one suggestions. But that code seems to have been there for ever so it might as well stay. Your call!