adaptive_permtest_quick_gs: Permutation test for adaptive group sequential trials
In floatofmath/adaperm: Permutation tests for adaptive designs

Quick no-nonsense permutation test for two-stage adaptive group-sequential trials that computes only the p-value

1 2	adaptive_permtest_quick_gs(x1, x2, xE, g1, g2, gE, a0, stat, permutations = 10000, restricted = T, stratified = T)

`x1`	first stage observations
`x2`	second stage observations
`xE`	extended stage observations
`g1`	frist stage treatment assignments
`g2`	second stage treatment assignments
`gE`	extended stage treatment assignments
`a0`	early rejection boundary
`stat`	test statistic to use
`permutations`	number of permutations to use
`restricted`	should the treatment group sizes be fixed
`stratified`