Integrate Slice Sampling: Hyperrectangles-based Methods.

[lorcandelaney]

See #772

Includes:

1. Hyperrectangles-based methods for Slice Sampling: Adaptive and Non-Adaptive. Both methods are in pints/pints/_mcmc/_slice_hyperrectangles.py.
2. Tests for Hyperrectangles-based methods.
3. Notebooks for Hyperrectangles-based methods.

[codecov[bot]]

Codecov Report

Merging #895 into master will not change coverage. The diff coverage is 100%.

@@          Coverage Diff          @@
##           master   #895   +/-   ##
=====================================
  Coverage     100%   100%           
=====================================
  Files          55     56    +1     
  Lines        5673   5772   +99     
=====================================
+ Hits         5673   5772   +99

Impacted Files	Coverage Δ
pints/_mcmc/_slice_hyperrectangles.py	100% <100%> (ø)

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[MichaelClerx]

Hey @lorcandelaney ! For these and other PRs, please check how your docstrings render, and if you're using the correct syntax (:math:`1 + x` for maths, ``1 + x`` for code) everywhere!

See CONTRIBUTING.md for instructions on locally building and inspecting the docs