Fixes #4.

Fix a bug where too many spaces would sometimes be removed.

Wait to decode bytes received from the server until a full line has
been received. Data received from the server could end in the middle
of a UTF-8 multibyte sequence, and decoding the data without waiting
for the rest of the line would result in a decoding error.

Docstrings don't have to be enclosed in triple quotes; update GPL
exception to apply to all strings to reduce confusion and licensing
issues.

Would crash if "=" was not present in an argument.

If event handlers take fewer arguments than are available,
an error will no longer occur.

Use RPL_ISUPPORT PREFIX and CHANMODES.

Methods should be case-insensitive.

Make sure default_factory is callable in IDefaultDict.__init__().

Add class VoiceOpInfo instead of setting attributes on IStr instances.
Make IRCBot.nicklist values IDefaultDict objects themselves -- each dict
maps an IStr nickname to a VoiceOpInfo object.

If an exception occurs in a daemon thread, it may cause the main thread to exit
(thus ending the program) before the daemon thread gets a chance to print out
the exception. So, print out tracebacks manually in background threads which
could be daemons.