Add a very basic implementation of adaptive permutation for the bootstrap testing in binomRVScoreEnvRare. If -numBootstraps is set to -1, start at 1000 bootstrap samples: every time the resulting CAST-style p-value approaches significance, increase the number of bootstraps by a factor of 10 and repeat (up to 100,000,000 samples). If the p-value is clearly not significant then stop processing this set of variants any further.