QR styling source attribution

SvgGenerator.php and Geometry.php port the behavior of qr-code-styling
1.6.0-rc.1, by Denys Kozak, together with the application's QR vector and
seamless-square patches. The pinned source bundle is retained in the C34
development reference; its SHA-256 is
5b5e816fb9ff694b6f1327105a3e7f202c84247a1140291f51af4666d9a2217a.

MIT License

Copyright (c) 2019 Denys Kozak

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 reused Fabric/Refabric curve normalization and notices are retained at
../../Scene/BoundedC13/PathGeometry.php and
../../Scene/BoundedC13-NOTICES.txt; no alternate native arc approximation is
substituted for that existing source-normalization port.
