Flarefly

Main changes included in this release:

- Introduction of possibility to dump the result in ROOT format
- Add possibility to plot residuals
- Add possibility to print additional info on plots
- Add Voigtian pdf for signal

See https://github.com/flarefly/flarefly/releases/tag/v0.0.6 for content

What's changed
Added
- the possibility to set several signal and background pdfs passing a list of them
- several signal functions (double Gaussian, double Crystalball, Cauchy)
- several background functions (Chebychev polynomials, power law, power low exponential)
- possibility to dump the data into an histogram
Removed
- the "second peak" feature
- the dictionary of particle properties (now taken from [Particle](https://github.com/scikit-hep/Particle))

See https://github.com/flarefly/flarefly/releases/tag/v0.0.5 for content

Dummy release for documentation deployment, see https://github.com/flarefly/flarefly/releases/tag/v0.0.1 for content

What's Changed
* Add class to handle data in different formats
* Add class to perform invariant-mass fits
* Add tests
* Add documentation