Tiny formatting.
Completely redid item comparison:
We now do the comparison ourselves (without relying on bukkit's built-in
isSimilar() method). This has the disadvantage that we need to update
for every new type of ItemMeta being added. But this also has the
advantage that we have more control over what is actually checked during
comparison: we should now be able to properly compare item attributes
(ignoring their individual uuids) and skull data (ignoring the
underlying texture data).
Added attribute comparison to NMS specific code.