Improve documentation of broadcast subpackage
Remove broadcaster goroutine
Some early primitive-broadcasting code
Overwrite PrimitiveBroadcaster.Send with specific type arg
Last intermediate work before ditching InfiniteChannel
Basic conversion to fixed-size Subscription channels
./broadcast/ overflow handling
Update state/broadcast enough to make tests pass
Use generic broadcaster for docstate
logic.Event.Apply() - will expand tests later
logic.Event.Goto() - also shoddy testing