BlueSky network overhaul.

[jooste]

Huge BlueSky networking update that:

• replaces event+stream four-port system to a simple two-port publish/subscribe topology. This:
  • Simplifies connection by other clients
  • Also allows sim-sim or client-client connections
  • creates more flexibility to divide clients and/or sims into communication groups
• Adds a generic way to specify state publishers.
  • Automatic periodic publishing of state (updates)
  • Allows requests for full state (e.g., for late joiners)
  • Automated storage of state data on the client side for multiple simulation nodes
• ActData: convenience accessors for simulation state data on the client side. Retrieve data from the currently active/selected simulation node as if it were member data.
• Single subscriber decorator for both local and networked signals.

Other updates:

• Small refresh of main user interface
• Centralised reference data
• Traffic proxy object for client-side accessing of bluesky.traf
• Probably more, this branch has been under development for more than two years!