Service is a some action which may be performed with different NPCs.
Storaging, buying and selling should use the nearest available NPC when NPC isn't configured.
Item lists with prices are needed.
There are standard buying lists, but some NPCs sell items using custom dialogs.
To be compatible, we need to store detailed NPC descriptions not in npcs.txt.
- Service name (storage, save, cartrent, sell, buy)
- Service fee
- Custom data (item lists and prices)
- NPC location
- NPC talk sequence
Other Required Features
- Select-response-by-text, select-response-by-regexp in NPC talk sequences