JEI Compat

[IchHabeHunger54]

This PR:

• Adds skills to the JEI item list
• Adds a new skill JEI category that lists the ingredients needed, the affinity breakdown and the compatible modifiers for a skill
• Sorts the prefab spell list
• Adds name-specific translations for the Etherium Placeholder item
• Does some rearrangements and cleanups in related code

[Minecraftschurli]

I'll have to try this out first