Generic validator for date ranges (date from - date to).
Will return FALSE if date2 < date1, requires two custom attributes named "date1" and "date2",
representing the field names of the two recordset fields to use
in the validation logic. Returns TRUE if any of the parameters is null.
Creation date: 29/10/2003
Last Update: 29/10/2003
(c) 2004 Martin Cordova
This code is released under the LGPL license
author: Martin Cordova (dinamica@martincordova.com)