v0.4.0: Refactored strength requirements, also changed how they scale

Also refactored class armor a bit so that it is upgradeable

src/com/shatteredpixel/shatteredpixeldungeon/items/weapon/melee/MagesStaff.java

@@ -196,8 +196,6 @@ public class MagesStaff extends MeleeWeapon {
 	@Override
 	public Item upgrade(boolean enchant) {
 		super.upgrade( enchant );
-		STR = 10;
-		//does not lose strength requirement
 
 		if (wand != null) {
 			int curCharges = wand.curCharges;
@@ -215,8 +213,6 @@ public class MagesStaff extends MeleeWeapon {
 	public Item degrade() {
 		super.degrade();
 
-		STR = 10;
-
 		if (wand != null) {
 			int curCharges = wand.curCharges;
 			wand.degrade();