Document some opcodes related to shops and implement a generic gil shopkeeper script
* You can now interact with shopkeepers, and if you have enough gil, you can attempt to purchase items
* Upon trying to buy items the event will auto-cancel for now, because we're missing implementations of several opcodes related to inventory management
-Global.lua is no longer a catch-all dumping ground for registering actions and events
Instead, Global.lua will actually contain useful global constants and functions
-Init.lua will take over the role of being the initial script run when doing reloads or booting the servers
-Actions.lua will take over registering all actions
-Items.lua will take over registering all items
-Commands.lua will take over registering all text commands
-Events.lua will take over registering all warps, openings/quests, aetherytes, etc.
To this end, event ids now live in organized tables to reduce error-prone copy paste clutter
If we get enough actions, items or commands, we can move those to tables too.
