Attempt to fix some minor memory leaks

src/connection.cpp

@@ -537,6 +537,14 @@ Connection::Connection(u32 protocol_id, u32 max_packet_size, float timeout,
 Connection::~Connection()
 {
 	stop();
+	// Delete peers
+	for(core::map<u16, Peer*>::Iterator
+			j = m_peers.getIterator();
+			j.atEnd() == false; j++)
+	{
+		Peer *peer = j.getNode()->getValue();
+		delete peer;
+	}
 }
 
 /* Internal stuff */

src/itemdef.cpp

@@ -290,8 +290,11 @@ public:
 		// Ensure that the "" item (the hand) always has ToolCapabilities
 		if(def.name == "")
 			assert(def.tool_capabilities != NULL);
-
-		m_item_definitions[def.name] = new ItemDefinition(def);
+		
+		if(m_item_definitions.count(def.name) == 0)
+			m_item_definitions[def.name] = new ItemDefinition(def);
+		else
+			*(m_item_definitions[def.name]) = def;
 
 		// Remove conflicting alias if it exists
 		bool alias_removed = (m_aliases.erase(def.name) != 0);