Merge branch 'master' into add-cpnest

.gitlab-ci.yml

examples/injection_examples/eccentric_inspiral.py

examples/other_examples/linear_regression_pymc3.py

...her_examples/linear_regression_pymc3_custom_likelihood.py

examples/other_examples/radioactive_decay.py

optional_requirements.txt

test/detector_tests.py

test/gw_likelihood_tests.py

test/gw_prior_tests.py

test/likelihood_tests.py

tupak/core/likelihood.py

tupak/core/prior.py

tupak/core/sampler.py

tupak/core/utils.py

tupak/gw/conversion.py

tupak/gw/detector.py

tupak/gw/likelihood.py

tupak/gw/prior.py

tupak/gw/prior_files/GW150914.prior

tupak/gw/prior_files/binary_black_holes.prior