thirdparty: vendor tomli The next commit will introduce a .toml file to abstract configitems away from Python. Python 3.11 has a toml read-only library (`tomllib`), which gives us a way out of vendoring eventually. For now, we vendor the backport, specifically version 1.2.3 which is still compatible with Python 3.6.

configitems: add `documentation` field It may be useful to expose documentation information in the help in some form. This will be populated in a future changeset by using the current comments that are relevant for users.

configitems: use standard "dynamicdefault" approach in edge case This makes for fewer edge cases, which will help a future patch.

configitems: fix typo in devel warning about extension overrides

extensions: imp module is removed in Python 3.12 - use importlib to load files imp has been deprecated for a long time, and has finally been removed in Python 3.12 . imp was only used for loading extensions that has been specified with direct .py path or path to a package directory. The same use cases can be achieved quite simple with importlib, , possiby with small changes in corner cases with undefined behaviour, such as extensions without .py source. There might also be corner cases and undefined behaviour around use of sys.modules and reloading.

utils: imp module is removed in Python 3.12 - get is_frozen() from _imp imp has been deprecated for a long time, and has finally been removed in Python 3.12 . The successor importlib is using the same internal _imp module as imp, but doesn't expose it's is_frozen. Using the internal function directly seems like the cleanest solution. Another alternative to imp.is_frozen("__main__") is sys.modules['__main__'].__spec__.origin == 'frozen' but that seems even more internal and fragile.