v0.9.2: adjusted missile weapon durability logic to use rounding

core/src/main/java/com/shatteredpixel/shatteredpixeldungeon/items/weapon/missiles/MissileWeapon.java

@@ -231,6 +231,8 @@ abstract public class MissileWeapon extends Weapon {
 		//at 100 uses, items just last forever.
 		if (usages >= 100f) return 0;
 
+		usages = Math.round(usages);
+		
 		//add a tiny amount to account for rounding error for calculations like 1/3
 		return (MAX_DURABILITY/usages) + 0.001f;
 	}