/* $DOC$
   $NAME$
      ft_FDay()
   $CATEGORY$
      Date/Time
   $ONELINER$
      Return first day of the month
   $SYNTAX$
      ft_FDay( [ <dDateToChk> ] ) -> dFirstDay
   $ARGUMENTS$
      <dDateToChk> is a date within a month for which you want to find
      the first date of that month.  If not passed or is an incorrect type,
      defaults to current system date.
   $RETURNS$
      A Clipper date value representing the first date of the month.
   $DESCRIPTION$
      This function will return the first day of the month of the date
      passed, or the first day of the current month if no argument is
      supplied.
   $EXAMPLES$
      ? ft_FDay( 0d19900915 )        // 1990-09-01
      ? ft_FDay()                    // 1991-03-01  (current month)
   $SEEALSO$
      ft_LDay()
   $END$
 */