Mod loading

[olefasting]

This PR adds mods to Fish Fight.

Currently, only data mods are allowed and they will currently extend the core resources (in the future we will add a replace option, for when creating total conversion mods). This means that a mods resources will be added to Resources, or overwrite existing resources, if ids are the same.

The mods directory holds two example mods that show how to create a mod and how dependencies work. These examples hold no actual content but this is added just like when adding to the assets dir, using the same resource file names and the same folder.

Mods are loaded in order, according to the order given in active_mods.json

All resources that are loaded dynamically are supported in mods:

• decoration (decoration.json)
• images (images.json)
• items (items.json)
• maps (maps.json)
• music (music.json)
• particle effects (particle_effects.json)
• player characters (player_characters.json)
• sounds (sounds.json)
• textures (textures.json)