Sets the uniform and normal random number generators and the seed.
The old setting is returned using invisible() in a format
which can be used in another call to setRNG. (This would reset to the
original value.) If no arguments are given the current setting is returned,
not using invisible(). In R see RNGkind for more details.
Note that in a function using setRNG it is good practice to
assign the old setting to a variable, then reset to the old value on exiting
the function (using on.exit). This avoids the possibility that
overall RNG behaviour in a session, other than within your function, may be
disrupted by your function.