See doc/copying/MPL-2.0.txt for the license.  The bulk of this code is under
the Mozilla Public Licese, version 2.0.  More formally:

  This Source Code Form is subject to the terms of the Mozilla Public
  License, v. 2.0. If a copy of the MPL was not distributed with this
  file, You can obtain one at http://mozilla.org/MPL/2.0/.
