alan-turing-institute/distr6: distr6 1.3.6

Bugfix in decorate function that was overwriting the decorators private field instead of appending Two bug fixes in MultivariateNormal$rand() . i) the distribution mean wasn't being added to the transformation correctly; ii) the Choleskey decomposition wasn't transposed causing incorrect simulations Added plot.VectorDistribution for more efficient plotting of mutiple distributions at the same tim