Handles dist / scalar (delegates to dist * (1/scalar)), scalar / dist, and dist / dist.
# S3 method for class 'dist'
x/yA simplified distribution or edist
# Division by scalar reuses multiplication rule
z <- normal(0, 4) / 2
z # Normal(mu = 0, var = 1)
#> Normal distribution (mu = 0, var = 1)