calckappa: calckappa
In jennasimit/MTFM: Multinomial fine-mapping

Calculate kappa for a given region and priors on the number of causal variants in the region, and the prior odds of causal variant sharing

1	calckappa(nsnps, p, ndis, target.odds)

`nsnps`	number of snps in the region
`p`	probability any snp is causal (assumes a binomial distribution for the number of causal snps, with expected number = p * nsnps)
`ndis`	number of diseases
`target.odds`	prior odds of NO SHARING of causal variants between a single trait and any of the other trait. ie a value < 1 indicates a prior expectation that no sharing is less likely than sharing.