Improve how dimmed power is transferred

[Rushmead]

Currently Dimmed power is transferred like any normal power cable, the power is pushed into any neighbouring power cables. This unfortunately means that when using the socapex distribution, only one light can be powered over a single cable.

I'd like to move this over to a more "networked" approach where the socapex distribution detects what is connected over a cable and then sends the actual intensity / power to the connected lights. This also allows us to add the ability to "overload" a socapex distribution or dimmer rack. The DMX cables currently work in this same way except the state of where cables are connected is stored in the World capability.

I don't really think that storing them in the world capability is a good idea, so I'd like to think of some other ways.