Break up Irc() into a state tracker and a socket-based subclass

[jlu5]

This would allow PyLink to establish virtual connections to non-IRC services (e.g. XMPP, Telegram)

• Break up connect(), connect loop threading, disconnect(), run(), and send() into an IRC specific class
  • Depending on the framework we're hooking into, 3rd-party transports may choose to skip run() and send() entirely.
  • xmpppy has its own registerHandler(), for example
• Call protocol specific disconnect code irc.proto.disconnect() if defined Split protocol specific and protocol agnostic connect/disconnect code
• Move schedulePing() into this new (IRC-specific) class, and possibly allow turning ping checks off entirely