Method for differentiating new broadcasters/queues

[schielb]

In the sound branch, I'm adding a new broadcaster for pygame.mixer. In the current setup, all broadcasters pull from the same output_queue from the demo that is currently running. That queue has no way of differentiating strings that are passed into it. This leaves the individual broadcaster to parse through the message and determine if it is an item to "broadcast".

Ideally, we should have alternate ways for a user creating a demo to control which broadcaster is receiving its info.

[schielb]

There are multiple ways we could try and do this. Two specific ones are:

• Sub-queues: the output_queue could have different sub-queues that the demo creator needs to differentiate between
• Sentinel values: Currently, every input to the output_queue.put method is going to be a string. We can inform the demo creator to put a sentinel value to start the string, something like "INFO " and "SOUND ", or so forth.

Predictably, there are pros and cons to both.