Add custom, random item drops

[jwflory]

Much like the original Super Smash Bros. game by Nintendo, adding item drops would add an interesting and challenging dynamic to matches. Items could be dropped such as a "home run bat" which has one hit left, but has Knockback X on it, or perhaps "PokéBalls" which are just renamed mob spawn eggs.

Bonus points if items (and their enchantments and damage) were configurable by server administrators in a YAML file.