WIP: Add timelock related methods on Transaction

Now we have the two `timelock` types we can implement a few methods on
`Transaction` that may be useful to users of the library.

src/blockdata/transaction.rs

@@ -40,7 +40,7 @@ use blockdata::witness::Witness;
 use consensus::{encode, Decodable, Encodable};
 use consensus::encode::MAX_VEC_SIZE;
 use hash_types::{Sighash, Txid, Wtxid};
-use VarInt;
+use {timelock, VarInt};
 
 #[cfg(doc)]
 use util::sighash::SchnorrSighashType;
@@ -609,6 +609,24 @@ impl Transaction {
     pub fn is_explicitly_rbf(&self) -> bool {
         self.input.iter().any(|input| input.sequence < (0xffffffff - 1))
     }
+
+    /// Returns the nLockTime as an absolute timelock.
+    pub fn absolute_lock_time(&self) -> timelock::Abs {
+        timelock::Abs::from(self.lock_time)
+    }
+
+    /// Return the nSequence for `input_index` as a relative timelock.
+    pub fn relative_lock_time(&self, input_index: usize) -> timelock::Rel {
+        timelock::Rel::from(self.input[input_index].sequence)
+    }
+
+    /// Returns `true` if this transactions nLockTime should be ignored.
+    pub fn ignore_lock_time(&self) -> bool {
+        if self.lock_time == 0 {
+            return true;
+        }
+        self.input.iter().all(|input| input.sequence == 0xffffffff)
+    }
 }
 
 impl_consensus_encoding!(TxOut, value, script_pubkey);