use less global state and sideeffects

[mattzque]

Right now rbot is quite the old code base of course, going into the future one obvious improvement to make is to refactor the core modules to use less global state:

• use ideally none, or very little (logging/config only) global variables / singletons / static class attributes
• remove import with side-effects, I already started with this, if I don't want to break/change existing plugins

This would make testing much easier and path the way for multi server support for example.