Moved trading and pricing code to another folder, separate files.
NPC: Added further inventory functionality.
Trading: Added price data structure, which allows for setting prices for items. Also includes some default definitions.
Dialogues: Improved way responses are being stored into table for each player.
Added support for multi option dialogue and the dialogue action as well. WIP in function action type.
Cleaned up code.
Modified NPCs so random dialogues are chosen on initialization.
Added function to start a dialogue, choosing randomly NPCs dialogues.
Changed NPC code to use new dialogue code