* [V3 Mod] Use a composite class for mod
This turns mod.py into acomposite class
I've split things in this up based on purpose, including `movetocore`
`movetocore` is a set of things which likely belong in the core bot and
not relying on mod being loaded.
This is part of #2500
Per discussion in discord, this should be the first thing in #2500
merged
* Move this back,
mod was importable,
and this was intended as non-breaking
* Prevent fix from being lost if merged before this.
see Cog-Creators/Red-DiscordBot#2510
* Move case creation to before sending
see #2515
* fix failed merge done in web
