Nanite

- feat: allow specifying the minimizer method for fitting (21)
- feat: new contact point estimation with linear fit for baseline
and polynomial fit for indentation part
- feat: new contact point estimation with Fréchet distance between
curve and direct path in normalized coordinates
- tests: rename experimental test data files according to
afmformats scheme (20)

- docs: preprocessing methods not correctly rendered

- fix: make sure that AFM metadata contain the spring constant and
raise a MissingMetaDataError if this is not the case
- ref: deprecate `IndentationPreprocessor` class in favor of a more
flat submodule (17)

- docs: add POC table to docs

- fix: do not modify preprocessing options when applying them (create
a copy of the dictionary)
- ref: remove `Indentation.reset` in favor of `AFMData.reset_data`

- feat: new contact point estimation method "fit_constant_polynomial"
which applies a piece-wise constant and polynomial fit
- feat: contact point estimation methods now return detailed
information about the procedure (currently plottable data to
understand the process)
- fix: spatial smoothing not working in some cases (15)
- enh: add `steps_optional` in preprocessing to allow fine-grained
control about order of application
- ref: remove "...smoothed" column data (which was never used anyway);
instead, apply smoothing directly to AFMData subclass
- ref: rename `require_steps` to `steps_required` in preprocessing
decorator
- setup: bump afmformats from 0.16.0 to 0.16.4