Adds numeric filter options for highest value (maximum) and lowest value (minimum) in results by using a sub query.

This module re-purposes the "min" and "max" fields in the filter configuration without renaming them. For Highest and Lowest options the field values should be field names to query.

There are 3 possible variations:

No values

Leaving both fields blank will select only the Highest or Lowest value and return one result.