Initial refactor and block closing.

ethcore/src/header.rs

@@ -131,7 +131,7 @@ impl Header {
 	/// Set the timestamp field of the header.
 	pub fn set_timestamp(&mut self, a: u64) { self.timestamp = a; self.note_dirty(); }
 	/// Set the timestamp field of the header to the current time.
-	pub fn set_timestamp_now(&mut self) { self.timestamp = now_utc().to_timespec().sec as u64; self.note_dirty(); }
+	pub fn set_timestamp_now(&mut self, but_later_than: u64) { self.timestamp = max(now_utc().to_timespec().sec as u64, but_later_than + 1); self.note_dirty(); }
 	/// Set the author field of the header.
 	pub fn set_author(&mut self, a: Address) { if a != self.author { self.author = a; self.note_dirty(); } }