Poxy

- added syntax highlighting for functions
- improved syntax highlighting of typenames

- fixed crash when tagfile is disabled
- fixed a few syntax highlighting edge-cases
- fixed non-determinism in XML output formatting
- improved performance of syntax highlighting post-process
- minor style fixes

- minor style fixes

- fixed `static` keyword sometimes appearing twice on variables
- fixed `constexpr` keyword sometimes leaking into variable type
- fixed newer versions of pygments adding unnecessary markup to whitespace
- fixed malformed trailing return types in some circumstances
- fixed changelog page sometimes not having a table-of-contents
- added support for C++20's `constinit`
- added fallback to `tomllib` or `tomli` if `pytomlpp` is not available
- added command-line options `--html`, `--no-html`
- added command-line options `--xml`, `--no-xml`
- added command-line option `--no-werror`
- added `CHANGES` to the set of candidate changelog filenames
- deprecated command-line option `--xmlonly`
- removed command-line option `--doxygen`

- fixed SVG inlining not preserving original image class attributes
- fixed `ValueError` when reading some SVG files
- fixed `navbar` option allowing duplicates
- fixed custom navbar items always being transformed to lowercase
- fixed navbar generating links to empty pages
- added `concepts` to the default set of links in `navbar`
- added `navbar` values `all` and `default`
- reduced I/O churn during HTML post-processing
- removed command-line option `--dry`

- added support for C++20 concepts