This also allows to assign a spell to multiple spell groups, which is the case for many spells in
the SRD.
Additionally, this makes many small improvements and fixes to the provided spell compendium.
World data (including compendium packs) is migrated automatically. In order to also migrate packs
provided by modules, you can use the following macro:
```js
const pack = game.packs.get("<name-of-the-module>.<name-of-the-pack>");
game.ds4.migration.migrateCompendiumFromTo(pack, 4, 5);
```
