possible Q spec error; not allowing block equal var cov

[eeholmes]

Q <- matrix("c", 4, 4)
diag(Q) <- c("ew")
Q[2:3,2:3] <- c("mo","cmo","cmo","mo")
Q[1,4] <- Q[4,1] <- "cew"

Errors were caught in is.marssMODEL()
 
Errors were caught in is.marssMODEL_marxss()
 The variance-covariance matrix Q is not properly constrained.
    Covariances between the same 2 variance pairs must be equal at t=1