Pyfuppes

- na1001 refactor:
- better pyright integration: define FFI1001 keys in `__init__` with defaults, to describe the types
- removed `__KEYS` and \_show; now part of `__str__` and `__repr__` where needed
- keys `HEADER` and `SRC` are now prefixed with and underscore to indicate private attrs
- add a setter for `V`, as dependent variables are internally stored in attr `_V`

- Python 3.11 compatible versions of numba JIT-compiled functions
- drop Python 3.8 support

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- avgbinmap / mean_day_frac: bugfix corner case mean day fraction is almost zero but < 0
- avgbinmap / add scipy based version of mean angle function

- revised v25 data cleaner

- numberstring: change output format of NumStr format analyser (to be used in f-string)

- na1001: add option to create FFI1001 from buffered IO