Kafe2

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.

* Fixed usage of TMinuit as backend (supported for Python 3 only).
* kafe2go support for manual bin heights.
* Implemented Simpson's rule for evaluating histogram bins. The model_density_func_antiderivative keyword has been replaced with the more general bin_evaluation keyword.

This is the second beta release of kafe2.

It includes bugfixes and some simplifying changes to the API. Here is a summary of the most important ones:

* *Fit*: `add_simple_error` was renamed to the simpler `add_error` and the signature for `limit_parameter` was changed to accept two independent keyword arguments for the upper and lower limits instead of a tuple
* *Plot*: the prefix `with_` was dropped from arguments to `plot()`
* new properties `label` and `axis_labels` were added to the `Container` classes and `model_label` was added to `Fit`
* histogram bin contents can now be set manually using new method `set_bins` in `HistContainer`.
* the name of the independent variable for `xy` and `hist` models is no longer required to be `x` and is instead taken from the first argument in the model function signature

This is the first public release of kafe2.

It has undergone a fair amount of testing and
should be sufficiently stable for most uses.
However, some bugs and limitations may still be
present in this version, so please open an issue
if you run into any problems.

Pre-release used for a thesis by Citiroller.
Contains generic multifits.
Does not contain generic nuisance parameters.