Some kind of pattern router

[drsm79]

There's weirdnesses in how the patterns get extended, which result in crufty code. Either there should be a pattern route, so an output know the name of the pattern, but doesn't get the object until after the patterns are fully initialised, or patterns should fire a ready event, and things get wired up when that happens.

[drsm79]

see also #53

[drsm79]

That would mean some intermediate object that knew the current pattern bank, all the outputs & the relationships between them. I think this is probably a pre requisite for #52, too