add extra checkbox for RBF

lib/transaction.py

@@ -675,6 +675,10 @@ class Transaction:
         s += int_to_hex(txin.get('sequence', 0xffffffff), 4)
         return s
 
+    def set_sequence(self, n):
+        for txin in self.inputs():
+            txin['sequence'] = n
+
     def BIP_LI01_sort(self):
         # See https://github.com/kristovatlas/rfc/blob/master/bips/bip-li01.mediawiki
         self._inputs.sort(key = lambda i: (i['prevout_hash'], i['prevout_n']))