cre2 source code copied from https://github.com/marcomaggi/cre2

Copyright (c) 2012, 2013, 2015-2017, 2019 Marco Maggi <marco.maggi-ipsu@poste.it><br/>
Copyright (c) 2011 Keegan McAllister<br/>
All rights reserved.

Redistribution  and use  in source  and  binary forms,  with or  without
modification, are  permitted provided that the  following conditions are
met:

1.  Redistributions  of source  code  must  retain the  above  copyright
   notice, this list of conditions and the following disclaimer.

2. Redistributions  in binary  form must  reproduce the  above copyright
   notice, this list  of conditions and the following  disclaimer in the
   documentation and/or other materials provided with the distribution.

3. Neither the name of the author  nor the names of his contributors may
   be used  to endorse  or promote products  derived from  this software
   without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ``AS
IS'' AND ANY  EXPRESS OR IMPLIED WARRANTIES, INCLUDING,  BUT NOT LIMITED
TO,  THE  IMPLIED  WARRANTIES  OF  MERCHANTABILITY  AND  FITNESS  FOR  A
PARTICULAR PURPOSE  ARE DISCLAIMED.   IN NO EVENT  SHALL THE  AUTHORS OR
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PROCUREMENT  OF SUBSTITUTE  GOODS OR  SERVICES;  LOSS OF  USE, DATA,  OR
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LIABILITY,  WHETHER IN  CONTRACT, STRICT  LIABILITY, OR  TORT (INCLUDING
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SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
