(broken during linkmauve refactoring)

- use the new PluginConfig.remove method to remove aliases
- do not do weird stuff when no args are provided
- do not flood when re-creating stored aliases

TODO: implement the remove_option method from configparser

(thanks eijebong)

(use automodule directive & docstrings)

Also:
- Add get_conversation_messages() to PluginAPI
- Make plugins_autoload colon-separated instead of space-separated
    (for consistency)
- Replace a JID() with a safeJID() in the uptime plugin

- add methods related to timed events to the PluginAPI
- remove parse_command_args_to_alias because str.format does that, and
  better
→ update the alias plugin

And fix some imprecisions/mistakes in the help.