Allow NestedSamples to take lists as well as numpy arrays as constructors

[williamjameshandley]

Description

Currently NestedSamples(data=...,logL=...,logL_birth=...) assumes that logL and logL_birth are numpy arrays. It shouldn't.

This adds a test which shows this behaviour, and then fixes with a quick conversion.

Checklist:

• I have performed a self-review of my own code
• My code is PEP8 compliant (flake8 anesthetic tests)
• My code contains compliant docstrings (pydocstyle --convention=numpy anesthetic)
• New and existing unit tests pass locally with my changes (python -m pytest)
• I have added tests that prove my fix is effective or that my feature works

[codecov]

Codecov Report

Merging #190 (e56dba5) into master (48d6bc4) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master     #190   +/-   ##
=======================================
  Coverage   95.65%   95.66%           
=======================================
  Files          17       17           
  Lines        1773     1775    +2     
=======================================
+ Hits         1696     1698    +2     
  Misses         77       77           

Impacted Files	Coverage Δ
anesthetic/samples.py	100.00% <100.00%> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 48d6bc4...e56dba5. Read the comment docs.

[lukashergt]

Looks good. Feel free to squash and merge.