Add sampler.py with Pymbar

[chrisjonesBSU]

This PR adds 2 functions:

1. An equilibration sampling function that uses pymbar timeseries to return the uncorrelated samples from an equilibrated region.
2. A function that checks if an array is considered equilibrated given some threshold

Still to do:

• Unit tests
• Doc strings

[codecov]

Codecov Report

Merging #17 (b64ee2d) into master (a8df0c6) will increase coverage by 0.02%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master      #17      +/-   ##
==========================================
+ Coverage   99.63%   99.65%   +0.02%     
==========================================
  Files           5        6       +1     
  Lines         273      293      +20     
==========================================
+ Hits          272      292      +20     
  Misses          1        1              

Impacted Files	Coverage Δ
cmeutils/sampling.py	100.00% <100.00%> (ø)

[chrisjonesBSU]

Unit tests have been added. Still need to add doc strings.

[jennyfothergill]

Looks like the test environment needs pymbar. I will update the testing worklflow like we did in ulipolyBinder, planckton, msibi, etc :)

[jennyfothergill]

LGTM! a couple minor comments

[jennyfothergill]

this threshold might be a bit high. In reproducibility study we found we needed to lower it from 0.75 to get reasonable run times.

[chrisjonesBSU]

Maybe set 0.50 as a default?