Dialogues, trading: Add lock and unlock upon starting/finishing an interaction.
Updated README with progress.
Pathfinding: Fix slight bug that avoid a map being generated if the difference of start and end positions' z coordinate is zero.
Places: Added functions for adding and getting places, and for finding places of specific types. Added beds, chairs and chest as places.
NPC: Added places map and action queue.
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.