Allow for NULL fd_sets in descriptor_UpdateSet()
Reimplement the entire chat module, creating
`struct chat' - a `type' of struct descriptor.
Remove CARRIER logging.
CONNECT logging now only logs "CONNECT" lines. CHAT logging
masks it with an entire log of the conversation.
Modem dialing is now asynchronous, including pauses
and timeouts :-)
The hooks in DoLoop() in main.c are *very* messy ! I'll have
to rewrite DoLoop fairly soon, so I don't care too much for the
moment. This code is pretty raw.
