fix filterByDistanceFrom(..)

In MySQL you can't use WHERE with a generated column, so using filterByDistanceFrom with the new 'Distance'-column crashes:
"Unable to execute SELECT statement 
[SELECT *, ABS(6371 * ACOS(x * COS(RADIANS(lat)) * COS(RADIANS(lng) - y) + z * SIN(RADIANS(lat)))) AS `Distance` FROM table WHERE Distance < :p1] 
[wrapped: SQLSTATE[42S22]: Column not found: 1054 Unknown column 'Distance' in 'where clause']"

Even the HAVING-clause, which works with newer MySQL versions could be used in this context, does not work with older versions.
So due to compatibility issues I think this file should be reverted (even if that means duplicated code...)