Added license.

COPYING

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+This software has been authored by an employee or employees of Los
+Alamos National Security, LLC, operator of the Los Alamos National
+Laboratory (LANL) under Contract No. DE-AC52-06NA25396 with the
+U.S.  Department of Energy.  The U.S. Government has rights to use,
+reproduce, and distribute this software.  The public may copy,
+distribute, prepare derivative works and publicly display this
+software without charge, provided that this Notice and any
+statement of authorship are reproduced on all copies.  Neither the
+Government nor LANS makes any warranty, express or implied, or
+assumes any liability or responsibility for the use of this
+software.  If software is modified to produce derivative works,
+such modified software should be clearly marked, so as not to
+confuse it with the version available from LANL.