extension to filter_name_db

[steven-buckley]

the filter_name...() functions are used to limit the number of cross join records that are progressed to pattern matching to improve performance by excluding any records that are unlikely to meet the scoring criteria.

An additional criteria has been identified during development for alternative versions:

• where the forename equals the surname

[steven-buckley]

This will require amendments to the wider process to pass the surname to this function as well as forename