Released to CTAN today: most notable change is the message formatting.
### Added
- `\g_msg_module_documentation_prop` (see #471)
- `\peek_remove_spaces:n`
### Changed
- Formatting of messages: now follows LaTeX2e closely
### Deprecated
- `\mg_interrupt:nn`, `\msg_log:n` and `\msg_term:n`
### Fixed
- Handling of inheritance for choice keys (fixes #483)