Configuration system

[korpse]

One solution here is to introduce a Channel item, that would store channel related metadata such as the active plugins, the topic separator; a Network item (currently this looks a lot like IRCBotConfig) that would store information like default timezone, channels to join, nickname, modes, etc.

Perhaps maybe a singleton Global (or Config?) item that would store any bot-global information. Something more specific than Channel might also be useful, although this kind of thing would probably be plugin-specific. I'm not sure about this at the moment.

API keys should not be stored on plugins, see #12.