small fixes

planner/src/solver.rs

@@ -222,15 +222,15 @@ impl<'a, V, K: Eq + Hash + Clone> Problem<'a, V, K> {
     }
     /// Returns all complete solutions, after visiting all possible outcomes using a stack (DFS).
     pub fn solve_all(&mut self) -> Vec<Solution<'a,V,K>>
-        where V: Clone + fmt::Debug,
-              K: Clone + fmt::Debug,
+        where V: fmt::Debug,
+              K: fmt::Debug,
     {
         self._solve(None) // No limit
     }
 
     pub fn solve_one(&mut self) -> Option<Solution<'a,V,K>>
-        where V: Clone + fmt::Debug,
-              K: Clone + fmt::Debug,
+        where V: fmt::Debug,
+              K: fmt::Debug,
     {
         self._solve(Some(1)).pop()
     }