- [PR#162](https://github.com/biojppm/c4core/pull/162):
  - charconv.hpp:
    - add implementation of `to_chars()` for raw char pointers
    - improve `from_chars()` for bool
    - minor simplification of `atoi_first()` and `atou_first()`
  - format.hpp:
    - simplify `boolalpha()` implementation
    - `catrs()`/`catseprs()`/`formatrs()`: resize to capacity before trying
    - fix `uncatsep()`: force `sep` as a `csubstr`, and enforce it
    - `cat()`/`catsep()`/`format()`: add tests to ensure repeated args
    - improve implementation of `fmt::left()`/`fmt::right()`. add `fmt::center()`
  - Improve doxygen comments
- [PR#163](https://github.com/biojppm/c4core/pull/163):
  - `to_chars()`:
    - ensure `char*`/`const char*` (using strlen) overloads accept null pointer
    - add implementation for `nullptr_t`
- [PR#164](https://github.com/biojppm/c4core/pull/164): 
  - Move `aalloc()` et al to new hdr/src c4/alloc.hpp
  - Fix shared library exports, which were causing a link error in lld-link on Windows (see [rapidyaml#600](https://github.com/biojppm/rapidyaml/issues/600)).
- [PR#165](https://github.com/biojppm/c4core/pull/165): `c4/std/span.hpp` missing from amalgamate.py.
