They're all syntax changes and renames. I've checked twice to make sure
I didn't miss any listeners or classes.
For future reference:
- Do `from discord.ext.commands import Cog` in all new cogs.
- Subclass the new class to Cog.
- New listeners should get the `@Cog.listener()` decorator.
Conveniently, there weren't any pre-execution methods that have been
renamed.
- added logging and listing of kick/ban/mute events
- add usernotes (.note to add a note to a user, .notes to fetch them)
- split off mod.py into many files, cleanup on many features
- renamed .listwarns to .userlog
- renamed .mywarns to .myuserlog
