Add license

We copy the copyright header from the top of nuweb.w

LICENSE

@@ -0,0 +1,92 @@
+
+Copyright (c) 1996, Preston Briggs
+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.
+
+Neither name of the product nor the names of its 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 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.
+
+
+Notes:
+Update on 2011-12-16 from Keith Harwood.
+-- @@s in scrap supresses indent of following fragment expansion
+-- @@<Name@@> in text is expanded
+Update on 2011-04-20 from Keith Harwood.
+-- @@t provide fragment title in output
+Changes from 2010-03-11 in the Sourceforge revision history. -- sjw
+Updates on 2004-02-23 from Gregor Goldbach
+<glauschwuffel@@users.sourceforge.net>
+-- new command line option -r which will make nuweb typeset each
+NWtarget and NWlink instance with \LaTeX-commands from the hyperref
+package. This gives clickable scrap numbers which is very useful
+when viewing the document on-line.
+
+Updates on 2004-02-13 from Gregor Goldbach
+<glauschwuffel@@users.sourceforge.net>
+-- new command line option -l which will make nuweb typeset scraps
+   with the help of LaTeX's listings packages instead or pure
+   verbatim.
+-- man page corrections and additions.
+
+Updates on 2003-04-24 from Keith Harwood <Keith.Harwood@@vitalmis.com>
+-- sectioning commands (@@s and global-plus-sign in scrap names)
+-- @@x..@@x labelling
+-- @@f current file
+-- @@\# suppress indent
+
+This file has been changed by Javier Goizueta <jgoizueta@@jazzfree.es>
+on 2001-02-15.
+These are the changes:
+LANG  -- Introduction of \NW macros to substitue language dependent text
+DIAM  -- Introduction of \NWsep instead of the \diamond separator
+HYPER -- Introduction of hyper-references
+NAME  -- LaTeX formatting of macro names in HTML output
+ADJ   -- Adjust of the spacing between < and a fragment name
+TEMPN -- Fix of the use of tempnam
+LINE  -- Synchronizing #lines when @@% is used
+MAC   -- definition of the macros used by LANG,DIAM,HYPER
+CHAR  -- Introduce @@r to change the nuweb meta character (@@)
+TIE   -- Replacement of ~ by "\nobreak\ "
+SCRAPs-- Elimination of s
+DNGL  -- Correction: option -d was not working and was misdocumented
+ --after the CHAR modifications, to be able to specify non-ascii characters
+   for the scape character, the program must be compiled with the -K
+   option in Borland compilers or the -funsigned-char in GNU's gcc
+   to treat char as an unsigned value when converted to int.
+   To make the program independent of those options, either char
+   should be changed to unsigned char (bad solution, since unsigned
+   char should be used for numerical purposes) or attention should
+   be payed to all char-int conversions. (including comparisons)
+
+--2002-01-15: the TILDE modificiation is necessary because some ties
+  have been introduced in version 0.93 in troublesome places when
+  the babel package is used with the spanish.ldf option (which makes
+  ~ an active character).
+
+--2002-01-15: an ``s'' was being added to the NWtxtDefBy and
+  NWtxtDefBy messages when followed by more than one reference.
+
+