Kafe2

On December 7th iminuit 2.0 was released.
kafe2 does currently not support the new interface. kafe2 won't use iminuit if a version >2 is detected

* Skip using iminuit if iminuit>2 (until we support the new interface)

If you still want to use iminuit with kafe2, please install iminuit 1.x with `pip install 'iminuit<2'`

This "2.2.2-1" release fixes an issue from "2.2.2" when retrieving the version from iminuit, when iminuit is <2.

* Added support for iminuit 2.
* Fixed parameter constraints not increasing ndf.
* Fixed shared errors for multifits.

Fixed several bugs, mostly related to MultiFit:

* Fixed a bug where some kafe2-internal caches weren't properly cleared.
* A debug log message being printed as a user warning when adding shared errors to a MultiFit.
* Issues when adding more than one shared error.
* Issues when creating a MultiFit from different fit types.
* Shared errors sometimes being added to the wrong fit.
* Shared x errors sometimes using the wrong scale for calculating derivatives.

Relative to the last pre-release:

* Expanded documentation.
* Fixed documentation LaTeX build not working.

Fixed a bug where plotting MultiFits created from chi2 fits without shared errors would result in a crash.

Pre-release of the last release before publication and therefore last release with subtractive changes to the user interface.

* All nuisance parameter related code has been removed as it was nonfunctional. It can still be found on the dev branch.
* Interface for XYFit was simplified: removed projected_foo in favor of the shorter names that are shared with the other fit classes.
* Implemented errors relative to model.
* The algorithm for all dynamic errors (relative model errors, x errors) is set with the *dynamic_error_algorithm* keyword in the fit constructor. The *x_error_algorithm* keyword has been removed.
* Fixed GoF values for non-saturated likelihood cost functions.
* Added *chi2_probability* as a fir property, is shown in reports and plots.
* Simpler kafe2go syntax for limiting, fixing, and constraining parameters and for specifying relative data errors.
* Various internal improvements.
* Various improvements to documentation.
* Some new examples, reorganized examples.