Process system message dispatch

The power of any actor system, especially when it comes to a changing network topology is in its message routing and dispatching. The Echo.Process system has a number of mechanisms for dealing with this:

Mechanism	Description
Tell	Send a message to a Process - This should be your preferred mechanism for communicating with processes
Ask	Request/response for processes - use this sparingly.
ProcessId	Holds a Process location address
Routers	A router is a Process that manage sets of 'worker' processes by routing the received messages, following pre-defined behaviours, e.g. Round-robin, broadcast, etc.
Dispatchers	Similar to routers but without the need for a router process, all routing is done by the sender
Registered processes	A sort of DNS for Processes, can also register dispatchers
Roles	A special type of dispatcher that's aware of the aliveness of cluster nodes and what their roles are