Add methods to Item/Actor APIs

[RazeLighter777]

The following methods should be added to Items/Actors, adding these will allow for making a fuller game.

• Eat / Drink method. Both return SNutrition.
• Dialogue method. Should return a dialogue object.
• Harvest method. Basically synonymous with pickup method.
• Message method.
• Query properties method.
• Get points from kill method. (for score system)