Document retroactive re-licensing of the original DXPC code (closes #30).

nxcomp/LICENSE

-Copyright (c) 2001, 2010 NoMachine - http://www.nomachine.com/.
+Copyright (c) 2001,2010 NoMachine - http://www.nomachine.com/.
+Copyright (c) 2000,2003 Gian Filippo Pinzari
 
 NXCOMP library and NX extensions to X are copyright of NoMachine.
 Redistribution and use of this software is allowed according to the
@@ -18,6 +19,8 @@ along with this program; if not, you can request a copy to NoMachine
 or write to the Free Software Foundation, Inc., 59 Temple Place, Suite
 330, Boston, MA  02111-1307 USA
 
+==============================================================================
+
 Parts of this software are derived from DXPC project. These copyright
 notices apply to original DXPC code:
 
@@ -29,9 +32,59 @@ THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
 WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
 MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 
-Copyright (c) 1995,1996 Brian Pane
+Copyright (c) 1995,1996,2000,2006 Brian Pane
 Copyright (c) 1996,1997 Zachary Vonler and Brian Pane
 Copyright (c) 1999 Kevin Vigor and Brian Pane
-Copyright (c) 2000,2006 Gian Filippo Pinzari and Brian Pane
+<crossed-out>Copyright (c) 2000,2006 Gian Filippo Pinzari and Brian Pane</crossed-out>
+
+All rights reserved.
+
+==============================================================================
+
+Update 2015-05-21 on the nature of the original DXPC license: The
+original DXPC code used to be available under a license which failed to
+explicitly grant the permission to modify, but was later retroactively
+re-licensed under the 2-clause BSD license (see
+README.on-retroactive-DXPC-license for the copyright owners' statements;
+see <https://bugs.debian.org/784565> for more details).
+
+In the course of discussion, it also became evident that Gian Filippo
+Pinzari never participated in any of the official DXPC releases, but
+rather worked on the forked code on the NoMachine side. Thus, we
+crossed-out his name in the above copyright notice and moved him to the
+top list of copyright holders associated with the GPL-2 re-licensing done
+by NoMachine.
 
+Thus, the version of DXPC where NXCOMP got forked from (most likely some
+DXPC version between release 3.7.0 and release 3.8.0) can be considered
+as BSD-2-clause, as quoted below:
+
+Copyright (c) 1995,1996 Brian Pane
+Copyright (c) 1996,1997 Zachary Vonler and Brian Pane
+Copyright (c) 1999-2002 Kevin Vigor and Brian Pane
 All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+* Redistributions of source code must retain the above copyright
+  notice, this list of conditions and the following disclaimer.
+
+* 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.
+
+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 REGENTS OR CONTRIBUTORS
+BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
+OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
+DAMAGE.

nxcomp/Misc.cpp

@@ -384,9 +384,9 @@ static const char CopyrightInfo[] =
 Copyright (c) 2001, 2010 NoMachine, http://www.nomachine.com/.\n\
 \n\
 NXCOMP, NX protocol compression and NX extensions to this software \n\
-are copyright of NoMachine. Redistribution and use of the present\n\
-software is allowed according to terms specified in the file LICENSE\n\
-which comes in the source distribution.\n\
+are copyright of NoMachine. Redistribution (modified or unmodified) and
+use of the present\n\ software is allowed according to terms specified in
+the file LICENSE\n\ which comes in the source distribution.\n\
 \n\
 Check http://www.nomachine.com/licensing.html for applicability.\n\
 \n\