Create separate extetnd.c file for handling extensions / %extend

This is just a simple code refactor, moving and function renaming to
remove the %extend code out of the parser into its own file now
 that it isn't just used in the parser.

Source/CParse/util.c

@@ -88,3 +88,17 @@ void cparse_normalize_void(Node *n) {
     }
   }
 }
+
+/* -----------------------------------------------------------------------------
+ * new_node()
+ *
+ * Create an empty parse node, setting file and line number information
+ * ----------------------------------------------------------------------------- */
+
+Node *new_node(const_String_or_char_ptr tag) {
+  Node *n = NewHash();
+  set_nodeType(n,tag);
+  Setfile(n,cparse_file);
+  Setline(n,cparse_line);
+  return n;
+}