fixed the loader timing out

Before, it would just move on and almost certainly jam itself. Now, it
remembers that it has a disc in the loader and just tries to shoot
again.
diff --git a/frc971/control_loops/index/index.h b/frc971/control_loops/index/index.h
index 28cad07..667aa79 100644
--- a/frc971/control_loops/index/index.h
+++ b/frc971/control_loops/index/index.h
@@ -317,6 +317,9 @@
   LoaderGoal loader_goal_;
   LoaderState loader_state_;
   int loader_countdown_, loader_timeout_;
+  // Whether or not we (might have) failed to shoot a disk that's now (probably)
+  // still in the loader.
+  bool disk_stuck_in_loader_;
 
   // Current state of the pistons.
   bool loader_up_;