worldspawn: Make sure it's only called once, to avoid multiple worldspawn entities (this can happen...) from messing everything up.

Source/Server/Main.c

@@ -256,7 +256,15 @@ worldspawn
 It's the map entity, literally
 =================
 */
+int g_initialized;
+
 void worldspawn( void ) {
+	
+	if (g_initialized) {
+		return;
+	}
+	g_initialized = TRUE;
+
 	int iMOTDLines = 0;
 	
 	// Let's load materials.txt because someone thought this was the best idea