WIP Replace sample odds ratio by unconditional MLE

The sample odds ratio is an biased estimate if it is close to zero. Use
therefore the unconditional maximum likelihood estimate like in R (see,
e.g. p. 135 in [1]  or p. 520 in [2])

[1] Anderson, Sharon Roe, et al. Statistical methods for comparative
studies: techniques for bias reduction. Vol. 170. John Wiley & Sons,
2009
[2] Hollander, Myles, Douglas A. Wolfe, and Eric Chicken. Nonparametric
statistical methods. Vol. 751. John Wiley & Sons, 2013.
WIP adapt tests and add optimization