* Redefined and renamed types for code units.
* Remove -Wsign-conversion from test builds.
* find_invalid and is_valid that work with C-style strings.
* Lifted the C++11 requirement for some functions
that take std::string as an argument.
* Support for C++20 u8string
Issue #89
* Update test docker image to 4.0.0
* Update Dockerfile to run tests with a recent gcc compiler.
* Make some internal helper functions non-template
* Add append16 function
Support for appending codepoints to existing utf16 encoded strings.
See #91
* next16
* Tests and documentation for next16
* Rewrite CMakeLists
Drop the existing CMake structure and write the new one from scratch. The root CMakeLists.txt is used for installing the package without building and running tests. Testing is done via a separate CMakeLists.txt in the tests directory.
* Remove "samples" directory.
The content of that file is already in the documentation.
* Update README.md
Restructure the reference, add installation instructions, toc, other minor changes
