Send currently playing streams to players when they join / Sync streams

[Vurv78]

If a stream is currently playing while someone joins, they should join and be able to hear it at the currently playing point. (Ok maybe not at the currently playing point that'd be really hard and require the server to predict where it's at in the song which might work?)

The creator of streamcore didn't wanna put effort into this and since we're the replacement naturally we have to do it....
Maybe make a new net message wa_sync that sends a ton of wa_create data.

[Vurv78]

Shouldn't be too hard now since we have a stopwatch on every stream