simplify detection of cycles in printer

src/prolog/machine/machine_state.rs

@@ -221,7 +221,6 @@ pub struct MachineState {
     pub(super) hb: usize,
     pub(super) block: usize, // an offset into the OR stack.
     pub(super) ball: Ball,
-    pub(super) redirect: CellRedirect,
     pub(super) interms: Vec<Number>, // intermediate numbers.
 }
 

src/prolog/machine/machine_state_impl.rs

@@ -50,7 +50,6 @@ impl MachineState {
             hb: 0,
             block: 0,
             ball: Ball::new(),
-            redirect: CellRedirect::new(),
             interms: vec![Number::default(); 256]
         }
     }
@@ -1618,9 +1617,9 @@ impl MachineState {
                 let addr = self[temp_v!(1)].clone();
                 self.ball.boundary = self.heap.h;
 
-                self.redirect = {
+                {
                     let mut duplicator = DuplicateBallTerm::new(self);
-                    duplicator.duplicate_term_and_redirect(addr)
+                    duplicator.duplicate_term(addr);
                 };
                 
                 self.p += 1;
@@ -2333,6 +2332,5 @@ impl MachineState {
         self.block = 0;
         
         self.ball.reset();
-        self.redirect.clear();
     }
 }