Make multiple types of ammo stop freaking out item examination

Looks like I introduced a bug with item hinting where having multiple valid types of ammo in your inventory would make the game ask you which kind you wanted, when examining the corresponding tool/gun. e.g., multiple types of 9mm ammo with a glock, or a sewing kit with both thread and sinew in your inventory.

This should probably be pulled into 0.4, since it's purely a bugfix, and is (IMO) a fairly annoying bug?