Add some benchmarks.
Do proper check in __setattr__
Remove opt.
Rename.

Rename.
Update tests.
Correct C module name.
More refactorings. Drop the handling for "_self_".
More cleanup, drop remaining `_self_` handling and drop all the `__qualname__` fiddling - seems it's not necessary at all: setattr(self, '__qualname__', crap) can't work without accompanying descriptor on the class (either slots-descriptor or property).
Add a dict-based implementation.
Simplify setattr
Skip some of the tests with the simple backedend. Fix some issues of the simple backend.