-system name getter

-added error checking for event handling in registerSystem
-now only valid handleEvent() functions are taken by system during register

source/ecs/system.d

@@ -74,6 +74,14 @@ struct System
         return m_id;
     }
 
+    /************************************************************************************************************************
+    *Get system name.
+    */
+    export const (char)[] name() nothrow @nogc
+    {
+        return cast(const (char)[])m_name;
+    }
+
     struct EventCaller
     {
         ushort id;
@@ -97,7 +105,7 @@ package:
     int m_pass;
 
     ///system name
-    char[] name;
+    char[] m_name;
 
     ///required components
     ushort[] m_components;