Event hooks for scripting

[dmlary]

Implement generalized way to add event hooks throughout the system.

Events of Interest

Room

• Entity enters (can be prevented)
• Entity leaving (can be prevented)

Object

• picked up/removed from container
• dropped/placed in another container
• equipped
• removed
• destroyed

Mobs

• entity (char/obj) enters same room
• entity (char/obj) leaving same room (can prevent)
• character speaks in room
• char speaks to mob

Hooks

• entity added to container; can be refused
• entity removed from container; can be prevented
• entity observes container arrival
• entity observes container departure; can be prevented