Fix random seed generation

[mcclearyj]

The default seed of 0 is very weak and the default number of random iterations is low; it's known that (1) certain pseudorandom number generators are sensitive to weak seeds, meaning that numbers will repeat more often than they should and (2) the first few iterations of a PRNG will be distinctly non-random.

The seed should be both configurable and the default set to an 128-bit value like Unix clock time.