Iminuit

Bug-fixes:
- sdist package was broken, this was fixed by henryiii

Implementation:
- Allow HESSE to be called without running MIGRAD first

Documentation:
- Added tutorial to show how iminuit can compute parameter errors for other minimizers

Other:
- henryiii added a CI test to check the sdist package and the MANIFEST

Bug-fixes:
- `draw_contour` now accepts an integer for `bound` keyword as advertised in the docs
- fixed wrong EDM goal in iminuit reports, was off by factor 5 in some

Interface:
- removed the undocumented keyword "args" in `(draw_)contour`, `(draw_)profile`
- removed misleading "show_sigma" keyword in `draw_contour`
- deprecated `Minuit.is_fixed`, replaced by `.fixed` attribute
- deprecated `Minuit.set_strategy`, assign to `Minuit.strategy` instead
- deprecated `Minuit.set_errordef`, assign to `Minuit.errordef` instead
- deprecated `Minuit.set_print_level`, assign to `Minuit.print_level` instead
- deprecated `Minuit.print_fmin`, `Minuit.print_matrix`, `Minuit.print_param`, `Minuit.print_initial_param`, `Minuit.print_all_minos`; use print() on the respective objects instead

Implementation:
- improved style of draw_contour, draw more contour lines
- increased default resolution for curves produced by `(draw_)mncontour`, `(draw_)contour`
- switched from internal copy of Minuit2 to including Minuit2 repository from GooFit
- build improvements for windows/msvc
- updated Minuit2 code to ROOT-v6.15/01 (compiler with C++11 support is now required to build iminuit)
- henryiii added support for building Python-3.8 wheels

Bug-fix release.

* Fix plotting when array_func is used (361)
* Sort input file list to make _libiminuit.so build reproducably (355)
* Fixed outdated links in the docs

- fixed wheels support
- documentation updates

- fix for broken display of Jupyter notebooks on Github when iminuit output is shown
- replaced brittle and broken REPL diplay system with standard `_repr_html_` and friends
- wheels support
- support for pypy-3.6
- documentation improvements

This release introduced unintended backward incompatibilities. These will be fixed soon, but for now please use v1.3.3.