<~ operator, target="jags"

For target="jags", the <~ operator is not working correctly. Example below.

```r
n <- 200
x1 <- rnorm(n,0,1)
x2 <- x1 + rnorm(n, 0, 1)
beta1 <- 0.5
beta2 <- 1
c <- beta1*x1 + beta2*x2
y <- rnorm(n, c, 0.1)

mJ <- bsem('y ~ c
           c <~ x1 + 1*x2',
           data = dat,
           sample = 1000,
           target = 'jags')
summary(mJ)
```