modes:pair:ord: make improper pairs worse than proper pairs

If the highcard of two pairs are equivalent, but one is improper while
the other is proper, the proper pair is always greater.

src/modes/pair.rs

@@ -67,8 +67,21 @@ use std::cmp::Ordering;
 
 impl Ord for Pair {
     fn cmp(&self, other: &Self) -> Ordering {
-        // We order pairs by their "best" member i.e. Pair::1
-        self.1.cmp(&other.1)
+        /*
+        Comparison is slightly complicated by the inclusion of wild cards.
+        Rules are as follows:
+        1) Two proper/improper pairs that have equivalent high cards are
+           equivalent.
+        2) Two pairs with equivalent high cards but only one is proper; the pair
+           that is proper wins.
+        3) Otherwise, comparison between high cards is the ordering.
+        */
+        match (self.1.cmp(&other.1), self.is_proper(), other.is_proper()) {
+            (Ordering::Equal, false, true) => Ordering::Less,
+            (Ordering::Equal, true, false) => Ordering::Greater,
+            (Ordering::Equal, ..) => Ordering::Equal,
+            (x, ..) => x,
+        }
     }
 }