Fix unstable tests

[FriesischScott]

This should fix the unstable tests for empirical distributions and mappings to standard normal space.

Closes #148.

[FriesischScott]

Something seems very wrong here. It fails the test for samples drawn from a normal. They aren't even transformed. How is the pvalue this low?

[FriesischScott]

Are hypothesis test just useless? Even if I sample a standard normal, the test will return anything between 0 and 1.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (580a502) 98.27% compared to head (fd4b2d1) 98.27%.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #149   +/-   ##
=======================================
  Coverage   98.27%   98.27%           
=======================================
  Files          27       27           
  Lines        1045     1045           
=======================================
  Hits         1027     1027           
  Misses         18       18           

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[FriesischScott]

While the hypothesis tests didn't work out, this at least improves the stability of the tests as far as I can tell.