Fix grenade rendering issues

Alpha blending was not working properly when rendered on the hotbar.
Items now rotate when they are dropped and have an appropriate
thickness.
Add localisation support for grenades.
Add registry for grenade types.

A registry is added that is responsible for adding new grenade types.
These types are then given a unique id and these ids are saved in a
file, so that grenades that are added in the future won't break existing
grenades in existing worlds.
Add recipe item to IGrenadeType interface
Load grenade types when initializing.

Grenade types are now registered and saved when the game is loaded.
Add (temporary) recipes for the new grenades.

Added some basic recipes that will probably change in the future, but at
least it shows the system is working.

Recipes need to be registered the "vanilla way", using the
registerCraftingRecipes() callback in IGrenadeType. Grenades in the
input recipe can be of any type and the properties of those grenades
will automatically be transferred to the output grenade.