Getting a functional seed method

[elbecerrasoto]

Currently the env.seed() method does not work.

What happens is that the propagation of the
seed, at environment creation, is not being done.

The seed must be used on all the places of
that use pseudorandom generation.

Implementing this would require adding a seed method
to each Operator, and feed it at env initialization time.

An approach would be bottom up. In which primitive Operators are tested for correctness on their seed initialization (same seed yields the same result). And building from there. The correctness of the final env would follow from composition of correct Operators. Some work using
this approach has been done.