- Removed "isClone" flag. This flag was error prone. The "core" classes now have decent copy constructors, and ideally long term we should create copy constructors for the abilities that have additional pointers in them.

-- The test suite passes but this is a big change. I might have introduced some memory leaks or bugs. I might have fixed some bugs, too

projects/mtg/src/ManaCost.cpp

@@ -274,8 +274,7 @@ ManaCost::ManaCost(ManaCost * manaCost)
     morph = NEW ManaCost( manaCost->morph );
     suspend = NEW ManaCost( manaCost->suspend );
 
-    // TODO: Need to figure out if a deep copy is necessary
-    extraCosts = manaCost->extraCosts;
+    extraCosts = manaCost->extraCosts ? manaCost->extraCosts->clone() : NULL;
 }
 
 // Copy Constructor 
@@ -301,8 +300,7 @@ ManaCost::ManaCost(const ManaCost& manaCost)
     morph = NEW ManaCost( manaCost.morph );
     suspend = NEW ManaCost( manaCost.suspend );
     
-    // TODO: Need to figure out if a deep copy is necessary
-    extraCosts = manaCost.extraCosts;
+    extraCosts = manaCost.extraCosts ? manaCost.extraCosts->clone() : NULL;
 }
 
 // operator=
@@ -674,6 +672,9 @@ int ManaCost::tryToPayHybrids(std::vector<ManaCostHybrid>& _hybrids, int _nbhybr
 //compute the difference between two mana costs
 ManaCost * ManaCost::Diff(ManaCost * _cost)
 {
+    if (!_cost) 
+        return NEW ManaCost(*this); //diff with null is equivalent to diff with 0
+
     int8_t diff[(Constants::MTG_NB_COLORS + 1) * 2];
     diff[Constants::MTG_NB_COLORS * 2] = Constants::MTG_NB_COLORS;
     for (int i = 0; i < Constants::MTG_NB_COLORS; i++)