Rough but working versions of Int.sign and Rat.sign.

Actually, these pass the spectest but the Rat.sign one is definitely returning the wrong thing.  Will try to correct both spectest and code shortly.

src/setting/Int.pm

@@ -32,6 +32,10 @@ class Int is also {
     our Complex multi method unpolar($angle) is export {
         Complex.new(self.Num * $angle.cos("radians"), self.Num * $angle.sin("radians"));
     }
+
+    our Int multi method sign() {
+        self.Num.sign.Int
+    }
 }
 
 multi sub abs(Int $x) { $x.abs }

src/setting/Rat.pm

@@ -48,6 +48,10 @@ class Rat {
     multi method abs {
         self < 0 ?? -self !! self;
     }
+
+    our Rat multi method sign() {
+        self.Num.sign.Rat
+    }
 }
 
 multi sub infix:<+>(Rat $a, Rat $b) {