## About The Pull Request
This PR refactors mind language holders into non-existence
As a result, `update_atom_languages` is no longer necessary
Mind-bound languages are transferred via `/mind/proc/transfer_to`
Species changing no longer deletes and re-creates the mob's language
holder, allowing them to keep any languages they have.
Species languages are sourced from `LANGUAGE_SPECIES` now, meaning they
are removed when they change species. If the mob is not a human with a
species datum, these are effectively just atom level languages.
Makes a bunch of unit tests to ensure language transfer over certain
events works as intended
## Why It's Good For The Game
Mobs with minds having two independent language holders results in a
good few bugs, and simply doesn't make sense when we have sources
(`LANGUAGE_MIND`).
Instead of tracking two language holders, we can simply use sources
better and only track one.
This means that the language holder you start with is your language
holder, period. It doesn't get deleted or re-instantiated or whatever.
## Changelog
🆑 Melbert
refactor: Refactored language holders, making species changes not delete
all of your known languages
/🆑
Loosely adapted from /vg/. This is an entity component system for adding behaviours to datums when inheritance doesn't quite cut it. By using signals and events instead of direct inheritance, you can inject behaviours without hacky overloads. It requires a different method of thinking, but is not hard to use correctly. If a behaviour can have application across more than one thing. Make it generic, make it a component. Atom/mob/obj event? Give it a signal, and forward it's arguments with a SendSignal() call. Now every component that want's to can also know about this happening.
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