Add exhaust which simply exhausts the iterator

This is useful for iterators which are simply used for their side
effects.

The new function is added to make intent clearer for places where you'd
previously call `count` or similar to exhaust the iterator.

Author: tbu-

src/lib.rs

@@ -1530,6 +1530,13 @@ pub trait Itertools : Iterator {
             |x, y, _, _| Ordering::Less == compare(x, y)
         )
     }
+
+    /// Exhaust the iterator by repeatedly calling `next()`.
+    fn exhaust(self)
+        where Self: Sized,
+    {
+        self.count();
+    }
 }
 
 impl<T: ?Sized> Itertools for T where T: Iterator { }