src/concaveman.cpp is a C++ port of the JavaScript that the R package concaveman 1.2.0 runs. The
ported code and its authors and licences:

concaveman (https://github.com/mapbox/concaveman), by Vladimir Agafonkin. ISC licence.

rbush (https://github.com/mourner/rbush), (c) 2015, Vladimir Agafonkin. MIT licence.

tinyqueue (https://github.com/mourner/tinyqueue), by Vladimir Agafonkin. ISC licence.

monotone-convex-hull-2d, robust-orientation, robust-sum, robust-subtract, robust-scale, two-product and two-sum
(https://github.com/mikolalysenko), by Mikola Lysenko. MIT licence.

point-in-polygon (https://github.com/substack/point-in-polygon), by James Halliday. MIT licence.

exp() and log() from V8 11.3 (src/base/ieee754.cc), which derive from fdlibm
  Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. Developed at SunSoft, a Sun Microsystems,
  Inc. business. Permission to use, copy, modify, and distribute this software is freely granted, provided that
  this notice is preserved.
  Modified by Google Inc.: Copyright 2016 the V8 project authors. All rights reserved. BSD 3-clause licence.

The ISC licence: Permission to use, copy, modify, and/or distribute this software for any purpose with or without
fee is hereby granted, provided that the above copyright notice and this permission notice appear in all copies.
THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
PERFORMANCE OF THIS SOFTWARE.

The MIT licence: Permission is hereby granted, free of charge, to any person obtaining a copy of this software and
associated documentation files (the "Software"), to deal in the Software without restriction, including without
limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of
the Software. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT
LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT
SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
DEALINGS IN THE SOFTWARE.

The BSD 3-clause licence (V8): 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 the name of Google Inc. 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 ARE DISCLAIMED.
