C14 integer polygon union and positive offsets — third-party notices

IntegerClipperEngine.php, IntegerClipperRecords.php and PathOffset.php translate
closed-polygon Clipper / ClipperOffset algorithms from clipper-lib/clipper.js:

  Author: Angus Johnson
  Clipper version: 6.4.2, 27 February 2017
  Copyright: Angus Johnson 2010-2017
  Website: http://www.angusj.com
  JavaScript translation: Timo, version 6.4.2.2, 8 September 2017

Use, modification and distribution are subject to the Boost Software License
version 1.0 reproduced in full below.

Upstream attributions:
  Bala Vatti, "A generic solution to polygon clipping", Communications of the
  ACM, Vol. 35, Issue 7 (July 1992), pp. 56-63.
  Max K. Agoston, Computer Graphics and Geometric Modeling: Implementation and
  Algorithms, Springer (2005).
  Chen and McMains, "Polygon Offsetting by Computing Winding Numbers",
  DETC2005-85513, ASME IDETC/CIE2005, pp. 565-575.

The port preserves the source scanline ordering and binary64 arithmetic in
its bounded integer domain. Internal PHP object/array records preserve the
source mutable identities; the facade adds input, output and work budgets.
No Tom Wu JSBN / Int128 source has been copied or translated: coordinates
are limited below Clipper's low-range threshold. Runtime uses only PHP source
and does not load frontend JavaScript, Node.js or development oracle files.

Boost Software License - Version 1.0 - August 17th, 2003

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Software, and to permit third-parties to whom the Software is furnished to
do so, all subject to the following:

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the above license grant, this restriction and the following disclaimer,
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