Adds boomerangs

Created by: unid15

• Added boomerangs. They can be crafted from 6 wooden planks, and deal devastating 25 damage when thrown, at the expense of being really hard to use (especially in closed spaces - even in the hallways).
• When thrown, boomerangs fly in a circle around the target - the farther away the target is from the thrower, the bigger the circle's radius (close up the radius is 1 turf, at the distance of 7 turfs the radius is 4). Then they return to the thrower
• The thrower will always catch the boomerang if it hits him.
• Toy boomerangs can be won from arcades