Support enforce_nonce and add random nonce for message creation

Author: Rapptz

discord/abc.py

@@ -26,6 +26,7 @@
 
 import copy
 import time
+import secrets
 import asyncio
 from datetime import datetime
 from typing import (
@@ -1614,6 +1615,9 @@ async def send(
         else:
             flags = MISSING
 
+        if nonce is None:
+            nonce = secrets.randbits(64)
+
         with handle_message_parameters(
             content=content,
             tts=tts,

discord/http.py

@@ -197,6 +197,7 @@ def handle_message_parameters(
 
     if nonce is not None:
         payload['nonce'] = str(nonce)
+        payload['enforce_nonce'] = True
 
     if message_reference is not MISSING:
         payload['message_reference'] = message_reference