Refnx

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- scale log-prior in log-posterior calculation using a multiplier. This allows
one to balance relative size of likelihood and prior.
- added Structure.from_slabs classmethod.
- fixed bug when trying to print a Parameter.

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- bump minimum Python version to 3.9.
- remove oldest-supported-numpy from list of build requirements.
- add "numba_parratt" reflectometry kernel. If numba is installed this kernel
has greater calculation speed (in calculating the reflectivity) under some
circumstances.
- fixed bug when exporting parameters from refnx GUI.
- use optionally installed black to format code fragment exported from refnx
GUI.
- update jax reflectivity kernel to fix deprecated functions.

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- remove roadblocks for building wheels for cp312.
- update vendored emcee.
- change str.format to f-strings.

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- allow detailed Q resolution kernel to work with q_offset.
- added lopx_hipx to ReductionOptions to allow one to specify the foreground
region.
- fix path concatenation issue in reduce_stitch, str or Path should be allowed.

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- automated the release to PyPI via Github Actions.
- removed setup.cfg, transferring all information to pyproject.toml.
- fixed various scipy DeprecationWarnings related to keyword only arguments.
- converted various os.path to pathlib.Path
- stopped writing xml output (nobody uses it?)
- added detailed resolution kernel calculation (writes out an HDF file).
Refactor detailed kernel calculator.
- removed np.asfarray usage, it's deprecated.
- updated emcee vendored code.
- silence RuntimeWarning if the foreground width is found to be wider than
predicted.
- fix pandas warnings in batchreduction.
- wholesale conversion of os.path to pathlib.Path. Hopefully not too many
bugs introduced as a result of this.

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- rudimentary HDF <-> Data1D interconversion. This is functionality that might
be subject to change, so the functions are prefixed by "_".
- added TOF simulation to reduction code.
- print out the fitting statistic in a tqdm progress bar.