std/time: add the Compare method to Time

std/time/time.jule

@@ -312,7 +312,23 @@ impl Time {
 
 	// Reports whether the time instant is before u.
 	fn Before(self, u: Time): bool {
-		ret self.sec < u.sec || self.sec == s.sec && self.nsec < u.nsec
+		ret self.sec < u.sec || self.sec == u.sec && self.nsec < u.nsec
+	}
+
+	// Compares the time instant t(self) with u. If t is before u, it returns -1;
+	// if t is after u, it returns +1; if they're the same, it returns 0.
+	fn Compare(self, u: Time): int {
+		mut tc, mut uc := self.sec, u.sec
+		if tc == uc {
+			tc, uc = i64(self.nsec), i64(u.nsec)
+		}
+		match {
+		| tc < uc:
+			ret -1
+		| tc > uc:
+			ret +1
+		}
+		ret 0
 	}
 
 	fn appendTo(self, mut b: []byte)!: []byte {