docs: public int[] columnMapping( String[] features ) {
      int[] map = new int[_colNames.length];
      for( int i=0; i<_colNames.length; i++ ) {
        map[i] = -1;              // Assume it is missing
        for( int j=0; j<features.length; j++ ) {
          if( _colNames[i].equals(features[j]) ) {
            if( map[i] != -1 ) throw new IllegalArgumentException("duplicate feature "+_colNames[i]);
            map[i] = j;
          }
        }
        if( map[i] == -1 ) Log.warn(Sys.SCORM,"Model feature "+_colNames[i]+" not in the provided feature list from the data");
      }
      return map;
    }