Computes the power of between-model likelihood ratio tests,
where power is defined as the probability of rejecting the null hypothesis when it is false.
A description of an analytical-numerical approximation approach can be found in:
Burnham, K.P., D.R. Anderson, G.C. White, C. Brownie and K.H. Pollock. 1987.
Design and Analysis Methods for Fish Survival Experiments Based on
Release-Recapture. Am. Fish. Soc. Monogr. 5, pages 216, 289-295.