Threading revision in cClientHandle

[xoft]

I did the first half of the task. I rewrote all the packets (ugh) for streaming and then made cServer use cSocketThreads for the client connections, but for now they're used only for reading. I'd be grateful if more people would test this (rev 244), as I could have overlooked something, potentially creating a crash or deadlock ability in some unusual circumstances. If I get no problem reports, I'll finish the sending part of this task tomorrow.