Smac

The main purpose of this release is to be synchronized with our upcoming paper.
Since many urgent features were already taken care of in 0.14.0, this release mainly focuses on better documentation and examples.

Features
* Examples and quickstart guide can now be generated by [sphinx-gallry](https://sphinx-gallery.github.io/stable/index.html).
* Added make command `make doc` and `make doc-with-examples`.

Major changes
* Examples are separated into categories.
* Renamed facade SMAC4BO to SMAC4BB (black-box).
* Add thompson sampling as a new acquisition function

Minor Changes
* Included linkcheck and buildapi to the `make doc` command.
* `quickstart.rst` was converted to `quickstart_example.py` to be processed by sphinx-gallery.
* Examples renamed from `*.py` to `*_example.py`, unless file name was `*_func.py`, in which case it was unchanged.
* Flake8 fixes for spear_qcp as there were a lot of complaints running `pre-commit`.
* Fixes pydoc issues.
* Fixed links in the README.
* Fixed warnings given during the doc build.
* Fixed inconsistent output shape described in `smac.epm.gaussian_process.GaussianProcess.sample_functions`
* Examples are wrapped inside `if __name__ == "__main__"`, fixing problems on mac.

Breaking Changes
* `BOHB4HPO` facade has been renamed to `SMAC4MF` facade (738)
* Require `scipy` >= 1.7 (729)
* Require `emcee` >= 3.0.0 (723)

Major Changes
* Drop support for Python 3.6 (726)
* Added Colab to try SMAC in your browser! (697)

Minor Changes
* Added gradient boosting example, removed random forest example (722)
* `lazy_import` dependency dropped (741)
* Replaced `pyDOE` requirement with `scipy` for LHD design (735)
* Uses scrambled Sobol Sequence (733)
* Moved to Github actions (715)
* Improved testing (720, 723, 739, 743)
* Added option `save_results_instantly` in scenario object to save results instantly (728)
* Changed level of intensification messages to debug (724)

Bug Fixes
* Github badges updated (732)
* Fixed memory limit issue for `pynisher` (717)
* More robust multiprocessing (709, 712)
* Fixed serialization with runhistory entries (706)
* Separated evaluation from get next challengers in intensification (734)
* Doc fixes (727, 714)

Minor Changes
* Improve error message for first run crashed (694).
* Experimental: add callback mechanism (703).

Bug fixes
* Fix a bug which could make successive halving fail if run in parallel (695).
* Fix a bug which could cause hyperband to ignore the lowest budget (701).

Major Changes
* Separated evaluation from get next challengers in intensification (663)
* Implemented parallel SMAC using dask (675, 677, 681, 685, 686)
* Drop support for Python 3.5

Minor Changes
* Update Readme
* Remove runhistory from TAE (663)
* Store SMAC's internal config id in the configuration object (679)
* Introduce Status Type STOP (690)

Bug Fixes
* Only validate restriction of Sobol Sequence when choosing Sobol Sequence (664)
* Fix wrong initialization of list in local search (680)
* Fix setting random seed with a too small range in Latin Hypercube design (688)

Minor Changes

* Use Scipy's Sobol sequence for the initial design instead of a 3rd-party package (600)
* Store start and end time of function evaluation (647)

Bug Fixes

* Fixes an issue in the Bayesian optimization facade which triggered an exception when tuning categorical
hyperparameters (666)
* Fixes an issue in the Gaussian process MCMC which resulted in reduced execution speed and reduced performance (666)

Bug Fixes

* Fixes the docstring of SMAC's default acquisition function optimizer (653)
* Correctly attributes the configurations' origin if using the `FixedSet` acquisition function optimizer (653)
* Fixes an infinite loop which could occur if using only a single configuration per iteration (654)
* Fixes a bug in the kernel construction of the `BOFacade` (655)