S3fit

Support to use the input photometric data to calibrate the input spectrum, e.g.,
to correct for aperture loss of the spectrum.

**Full Changelog**: https://github.com/xychcz/S3Fit/compare/v2.2.0...v2.2.1

A major updates of S³Fit.
(1) the linear fitting in log space is revised;
(2) an annealing optimization is included to provide a rough global solution, which is transferred to non-linear least-square optimization for fine tuning;
(3) the estimation of calibration error is updated with an iterative process;
(4) the convolution with variable kernel width is supported to account for a wavelength-dependent spectral resolution;
(5) the output formats are revised to provide a more user-friendly access.

- The manuals for basic and advanced usages as well as the example Jupyter Notebook are updated to reflect the latest version.
- An additional manual page is added for a full list of available parameters of S³Fit.
- The flowchart of S³Fit's fitting pipeline is updated, while the strategy page is still being edited.

**Full Changelog**: https://github.com/xychcz/S3Fit/compare/v2.0.4...v2.2.0

Update manuals and result output functions.

**Full Changelog**: https://github.com/xychcz/S3Fit/compare/v2.0.3...v2.0.4

Update description in readme.

**Full Changelog**: https://github.com/xychcz/S3Fit/compare/v2.0.2...v2.0.3

**Full Changelog**: https://github.com/xychcz/S3Fit/compare/v2.0.1...v2.0.2

1. Split codes into modules.
2. Support pip installation.

**Full Changelog**: https://github.com/xychcz/S3Fit/compare/v1.6...v2.0.1