Random number functions

array's random number functions allow arrays to be filled with random
numbers efficiently in a single call. Most of these functions use the
`array_urand`

uniform random object (of type urand), which is
accessible from TCL. The `fillgrand()`

function makes use of the
TCL accessible `array_grand`

object, which is
of type gaussrand.

- void
`fillrand`(array*x*)Fill

*x*with random numbers from the uniform distribution over - void
`fillprand`(array*x*)Fill

*x*with random numbers from the Poisson distribution - void
`fillgrand`(array*x*)Fill

*x*with random numbers from the Gaussian distribution - void
`fill_unique_rand`(array*x*, int*max*)Fill

*x*with random integers from the range [0..*max*] such that no two integers are the same.