netrw tools:
    Jiri Denemark
    mailto:jirka@ics.muni.cz
    http://www.fi.muni.cz/~xdenemar/netrw

MD5 message digest implementation
    public domain code written by Colin Plumb, 1993
    taken from mhash library (http://mhash.sourceforge.net/)

getopt function implementation (see src/getopt* for details)
    Free Software Foundation, Inc, 1987-1996, 1998-2001

