Changes for upper and lower errors when determining fundamental parameters.

[SherelynA]

Addresses issue #88 by calculating upper and lower error for evolutionary model derived parameters using the already integrated Monte-Carlo approach along with using a 68% central confidence interval. The method used is described in Suárez & Metchev (2022).

I was unable to run tests for the changes nonetheless, in the future tests should be written for these additions.

[kelle]

Now that tests are re-running, let's put this on hold until we can more of the old tests to pass.