This commit changes the way Equippable wrappers are created, such that
they more closely match the way class chest armor pieces are "guessed".
That is, instead of looking directly at the Material value of the given
item, we instead look at the name _suffix_, i.e. the part after the last
underscore in the name, e.g. `BOOTS` in `IRON_BOOTS`.
The neat thing about this approach is that it is compatible with future
items that follow the same naming convention, such as Netherite armor
pieces.
The downside is that it is stringly typed and not particularly "pretty",
and if the naming convention breaks or new items are introduced (such as
the elytra), we will have to make modifications anyway.
Fixes#636
Andreas Troelsen
7fc0473a72