Data arrival method rewritten

- Booleans (loggedIn, firstPing, nickSent, userSent, FirstRun) moved to
global definitions
- Removed old packet-based stream reader method
- Added new stream reader method that reads one character at a time.
Splits on newline. Should solve issue about PING arriving in the same
packet as another message and not getting processed
- Moved login checks/operations (USER sending, NICK sending, etc) to
separate Sub (doLogin)
- Moved PING checking to new Sub (cmdCheckPing)
- Added check for being logged in before checking messages