Add missing bool header.
Re-add license.
Rewrite cbare.

- Don't depende on Meson and Python.
- Simplify (de)serialization APIs.
- Simplify tests (don't generate from text files).
- Add a man page (cbare.3).
- Build on OpenBSD.
Use error_is_set.
Add build status to readme.
Add Arch Linux build.
Add Alpine build script.
Fix bugs spotted by doanalyze.sh.
Buildable in clang.
Add more scripts.
Check another item off the todo list.
Allow calloc and free functions to be set.
Remove unused state member from bare context.