Rethink approach to managing random

[oubiwann]

With the creation of a state-manager (gen_server; see #64), now's the right time to re-think how we're managing and using random seeds and random state.

Tasks:

• Identify the different ways in which we want to use random seeds
• Define those as configuration / options
• Initialise the seed(s) as appropriate in the gen_server
• Add functions for updating or viewing the seed(s)
• Examine current usage
• Add wrapping functions for the rand capabilities we need
• Refactor code to use new wrappers

Depends upon #64

[oubiwann]

Let's see ... it would be nice to:

1. always get the same image / noise when given a seed
2. always get the same series of noise data when given a starting seed
3. get something completely random, no matter what (if so desired)

I think we can collapse the first two into one. So we want seed and no-seed, really.

[oubiwann]

These are two different sets of functions in Erlang's rand module ... but we should be able to wrap those as one set, and dispatch based upon config / setup / state.

[oubiwann]

We're currently only using these:

• rand:seed_s
• rand:uniform_s

The first appears in loise-opts and we basically want to keep that free from references to the state gen_server ... per #62. Maybe? (just added a note to that ticket)

Arguably, the function in which it appears (update-perm-table) may not really belong in loise-opts ...

The second call allears in loise-util in the random-permutation-tablewhich is called by the same update-perm-table as above :-(

So, yeah -- this is deeply tangled with #62 ...

[oubiwann]

We don't need this right now; gonna backlog it ...