Rémi Verschelde 08efd1c908
COPYRIGHT: Update with recent additions, cleanup
Also include public domain assets in `COPYRIGHT.txt` with Unlicence text or
dual-licensing scheme.

And document commit hashes for most thirdparty code in `thirdparty/README.md`
for clarity, and in case there's no tag matching the included version numbers.

(cherry picked from commit c6802a65c6eba96ec033f46a4e9162abbe738d28)
2021-01-13 16:17:08 +01:00
..
2020-11-17 16:42:42 +01:00
2020-11-17 16:42:42 +01:00
2020-11-17 16:42:42 +01:00