Use generic lists for todo items.

Use the new generic list implementation instead of "next" pointers in
todo items.

Signed-off-by: Lukas Fleischer <calcurse@cryptocrack.de>

src/dmon.c

@@ -173,6 +173,7 @@ dmon_start (int parent_exit_status)
   apoint_llist_init ();
   recur_apoint_llist_init ();
   event_llist_init ();
+  todo_init_list ();
   io_load_app ();
   data_loaded = 1;