sleep command

[padawin]

needs to be in a inn (not implemented yet) or outside a town, dungeon or cave. if outside, requires a sleeping bag (constant item, not disposable, not implemented). heals player. should be able to choose sleep duration (in tick). during each tick must check for enemies following probability of the area / 2. duration must be: integer (nb ticks) or "heal" (sleep until healed, default)