Evaluate exchanging Actor with Worker as cell backend

[themue]

Worker allows larger dynamic queues and improved graceful shutdown than Actor. But it needs another goroutine. So in larger cell models the number of infrastructure goroutines would double. So effect on memory and performance regarding ops/sec has to be compared.

Alternatively a Cell could work with native language syntax and use individual goroutines to connect to it's subscribes. Those could use the same mechanism as the simple worker queue.