Defining the protocol at runtime

[malfuu]

Currently, the user-defined protocol is entirely specified through App in AppRuleExt.
This restricts the user to either:

• declare the protocol at app setup
• use a two stage runner (i.e. first run() to gather required components, second run() to play the game).

It would be good to support defining protocol during runtime -- allowing a user for example to go into some mods menu and toggle a bunch of scripts.

If we chose to go forward with this, attention must be given to:

• protocol relying on registration order
• protocol cannot be altered during a connection

I would suggest doing this in seperate steps:

• Take the AppRuleExt implementation to World instead, with AppRuleExt calling them instead.
• Provide a way to reset the protocol.
• Avoid relying on registration order. (Ord on ComponentId might be trick here?)