Implement UI to 'throw' an item

[skleinjung]

• Add new menu option
• All items have a throw range of '3'
• Enter a 'targeting' mode in the UI
• As cursor is moved, cast a ray in the direction of the target. Highlight the squares that are 'in range' and not blocked. Use 'blocks line of sight' property of terrain to determine if it blocks or not
• Animate the projectile before processing result