Organize logging, add some toggles.

[creesch]

Currently the entire thing spams a bunch of logging in both the minecraft client and the browser.

The browser console I don't really mind, it doesn't go anywhere though with fast moving chat it might become difficult to spot errors more easily.
For the minecraft side of things it might be annoying for people wanting to debug other mods as well.

To me the most straightforward way to handle this is to handle a debug toggle in the settings which will turn on more logging.

So some thought should go into

• the log level of various log messages currently in use.
• any messages we might specifically want to add for a debugging switch.
• how we want to implement this. Seems like it might make sense to add this to the named logger class.