rework query dispatch and execution - part I

[kukeiko]

What

Rework current mechanism so that an EntitySource can respond multiple times (Observable) instead of just once (Promise)

Why

To allow for a more complex EntitySource/EntitySourceGateway scenarios

[kukeiko]

I applied the idea I had years ago, where for a given query a stream would be established that sends packets with:

• data
• accepted queries
• rejected queries

The ability to respond multiple times to a query is vital to support using entity-space on both client + server, as it gives the EntitySourceGateway - which takes a Query to dispatch it - much more power and flexibility.