Add OP_CHECKSEQUENCEVERIFY (OP_NOP3)

See bip112:
https://github.com/bitcoin/bips/blob/master/bip-0112.mediawiki

Author: kanzure

bitcoin/core/script.py

@@ -235,6 +235,7 @@ def __new__(cls, n):
 OP_NOP2 = CScriptOp(0xb1)
 OP_CHECKLOCKTIMEVERIFY = OP_NOP2
 OP_NOP3 = CScriptOp(0xb2)
+OP_CHECKSEQUENCEVERIFY = OP_NOP3
 OP_NOP4 = CScriptOp(0xb3)
 OP_NOP5 = CScriptOp(0xb4)
 OP_NOP6 = CScriptOp(0xb5)
@@ -357,6 +358,7 @@ def __new__(cls, n):
     OP_NOP2: 'OP_NOP2',
     OP_CHECKLOCKTIMEVERIFY: 'OP_CHECKLOCKTIMEVERIFY',
     OP_NOP3: 'OP_NOP3',
+    OP_CHECKSEQUENCEVERIFY: 'OP_CHECKSEQUENCEVERIFY',
     OP_NOP4: 'OP_NOP4',
     OP_NOP5: 'OP_NOP5',
     OP_NOP6: 'OP_NOP6',
@@ -477,6 +479,7 @@ def __new__(cls, n):
     'OP_NOP2': OP_NOP2,
     'OP_CHECKLOCKTIMEVERIFY': OP_CHECKLOCKTIMEVERIFY,
     'OP_NOP3': OP_NOP3,
+    'OP_CHECKSEQUENCEVERIFY': OP_CHECKSEQUENCEVERIFY,
     'OP_NOP4': OP_NOP4,
     'OP_NOP5': OP_NOP5,
     'OP_NOP6': OP_NOP6,
@@ -1152,6 +1155,7 @@ def SignatureHash(script, txTo, inIdx, hashtype, amount=None, sigversion=SIGVERS
         'OP_NOP2',
         'OP_CHECKLOCKTIMEVERIFY',
         'OP_NOP3',
+        'OP_CHECKSEQUENCEVERIFY',
         'OP_NOP4',
         'OP_NOP5',
         'OP_NOP6',