- exported a few more functions.

- refactored the ModifyDamage interface to be more scripting friendly.

In general it should be avoided having to call directly into chained inventory functions because they are very problematic and prone to errors. So this got wrapped into a single handler (on AActor, not AInventory!) which will later make it easier to refactor the parameters of ModifyDamage to work better for scripting and avoid the chaining.

src/g_shared/a_pickups.cpp

@@ -822,6 +822,29 @@ AInventory *AInventory::CreateCopy (AActor *other)
 	return copy;
 }
 
+DEFINE_ACTION_FUNCTION(AInventory, CreateCopy)
+{
+	PARAM_SELF_PROLOGUE(AInventory);
+	PARAM_OBJECT(other, AActor);
+	ACTION_RETURN_OBJECT(self->CreateCopy(other));
+}
+
+AInventory *AInventory::CallCreateCopy(AActor *other)
+{
+	IFVIRTUAL(AActor, CreateCopy)
+	{
+		VMValue params[2] = { (DObject*)this, (DObject*)other };
+		VMReturn ret;
+		VMFrameStack stack;
+		AInventory *retval;
+		ret.PointerAt((void**)&retval);
+		stack.Call(func, params, 2, &ret, 1, nullptr);
+		return retval;
+	}
+	else return CreateCopy(other);
+}
+
+
 //===========================================================================
 //
 // AInventory::CreateTossable
@@ -1538,7 +1561,7 @@ bool AInventory::TryPickup (AActor *&toucher)
 	{
 		// Add the item to the inventory. It is not already there, or HandlePickup
 		// would have already taken care of it.
-		AInventory *copy = CreateCopy (toucher);
+		AInventory *copy = CallCreateCopy (toucher);
 		if (copy == NULL)
 		{
 			return false;