calc_bern_prob_binary: Calculate a bernoulli probability for assigning e_it = 0 v....
In fboehm/mitra2013:

Calculate a bernoulli probability for assigning e_it = 0 v. 1.

1	calc_bern_prob_binary(evec, Gvec, beta, betavec, y, theta)

`evec`	a vector e[-i, t] from the e matrix
`Gvec`	a vector G[-i, i] from the graph matrix G
`beta`	a scalar (on the diagonal) beta[i, i] from beta matrix
`betavec`	a vector betamat[-i, i] from beta matrix
`y`	a scalar, the [i,t] entry of data matrix
`theta`	sampling parameters, a list