/**
  * Gets an settler sequence.
  *
  * @param file The file of the sequence.
  * @param seqnumber The number of the sequence in the file.
  * @return The settler sequence.
  */
 public Sequence<? extends Image> getSettlerSequence(int file, int seqnumber) {
   DatFileSet set = getFileSet(file);
   if (set != null && set.getSettlers().size() > seqnumber) {
     return set.getSettlers().get(seqnumber);
   } else {
     return ArraySequence.getNullSequence();
   }
 }
  /**
   * Gets a given gui image.
   *
   * @param file The file the image is in.
   * @param seqnumber The image number.
   * @return The image.
   */
  public SingleImage getGuiImage(int file, int seqnumber) {
    DatFileSet set = getFileSet(file);

    if (set != null) {
      return (SingleImage) set.getGuis().getImageSafe(seqnumber);
    } else {
      return NullImage.getInstance();
    }
  }
  /**
   * Gets a landscape texture.
   *
   * @param file The file number it is in.
   * @param seqnumber It's sequence number.
   * @return The image, or an empty image.
   */
  private SingleImage getLandscapeImage(int file, int seqnumber) {
    DatFileSet set = getFileSet(file);

    if (set != null) {
      Sequence<LandscapeImage> landscapes = set.getLandscapes();
      if (seqnumber < landscapes.length()) {
        return (SingleImage) landscapes.getImageSafe(seqnumber);
      }
    }
    return NullImage.getInstance();
  }