/* $DOC$
   $NAME$
      ft_DayToBoW()
   $CATEGORY$
      Date/Time
   $ONELINER$
      Calculate no. of days between date and beginning of week
   $SYNTAX$
      ft_DayToBoW( [ <dGivenDate> ] ) -> nDays
   $ARGUMENTS$
      <dGivenDate> is any valid date in any valid date format.
      Defaults to current date if not supplied.
   $RETURNS$
      A positive number of days to beginning of week, range 0 to 6.
   $DESCRIPTION$
      ft_DayToBoW() returns the number of days to the beginning of the
      week.  Normally this will be one less than the value that
      would be returned by the Clipper function DoW(), unless the
      day for the beginning of the week has been changed with
      ft_DateCnfg().
   $EXAMPLES$
      dDate := hb_SToD( "19900915" )

      ? DoW( dDate )               // 7
      ? CDoW( dDate )              // Saturday
      ? ft_DayToBoW( dDate )       // 6

      // change beginning of week to Friday  (yeah!)
      ft_DateCnfg( , 6 )
      ? DoW( dDate )               // 7
      ? CDoW( dDate )              // Saturday
      ? ft_DayToBoW( dDate )       // 1
   $SEEALSO$
      ft_DateCnfg(), ft_AcctWeek(), ft_Week()
   $END$
 */