Moved code that orchestrates everything into a class called RunIRC.

Also some tidying up.
Fixed broken spec tests.
More filtering is now done by an instantiated object.
Re-factored parsing and protocol handling.

BotMsg gets its own file.
Reworked the help system, 3 levels: global, topic, subtopic.

See comment in Bot#help and Bot#cmd which dispatches to help.
Help should only work for a module if it is in @modules.