/* $DOC$
   $NAME$
      ft_FindITh()
   $CATEGORY$
      String
   $ONELINER$
      Find the "ith" occurrence of a substring within a string
   $SYNTAX$
      ft_FindITh( <cCheckFor>, <cCheckIn>, <nWhichOccurrence> ;
                  [, <lIgnoreCase> ] ) -> <nStringPosition>
   $ARGUMENTS$
      <cCheckFor> is the string to search for.

      <cCheckIn> is the string to search.

      <nWhichOccurrence> is the number of the occurrence to find.

      <lIgnoreCase> is a logical indicating if the search is to be case
         sensitive.  The default is no case sensitivity (.T.).
   $RETURNS$
      The position in the string cCheckIn of the ith occurrence of cCheckFor.
   $DESCRIPTION$
      This function finds the position in a string of the "ith" time another
      string appears in it.
   $EXAMPLES$
      // Find the Position in cMemoString of
      // the 10th Occurrence of "the", case
      // insensitive

      ? ft_FindITh( "the", cMemoString, 10 )
   $SEEALSO$
      ft_At2()
   $END$
 */