01/04/2005:  CUBIC program has been changed from closed source to open source.
04/27/2005:  5 options have been added: -D, -P, -F, -rr, -ir.
             CUBIC has been modified so that it will handle those input file
             containing 'N' or any characters other than "ACGT".
06/06/2005:  Fixed a bug which causes segmentation fault.