Makes the x/x/4 Armor Piercing Darts upgrade for the Monkey Sub actually live up to its name by allowing the tower to pop Lead Bloons.
Since this change is more about flavor than literal balance, price of the upgrade is configurable.
Also configurable is a setting for improving the x/2/4+ Heat-tipped Darts cross-path, which would otherwise be obsolete with this mod (default damage bonus is +1).
