Add heartbeat_timeout to the Client options.

This setting configures how long before a timeout event is emitted
internally and disconnects the websocket. Since some users were
experiencing issues with the gateway not responding, this should help
mitigate the issue for those with poor PCs.

discord/state.py

@@ -64,6 +64,7 @@ class ConnectionState:
         self.shard_count = None
         self._ready_task = None
         self._fetch_offline = options.get('fetch_offline_members', True)
+        self.heartbeat_timeout = options.get('heartbeat_timeout', 60.0)
         self._listeners = []
 
         game = options.get('game', None)
@@ -907,7 +908,6 @@ class AutoShardedConnectionState(ConnectionState):
             launch.set()
             yield from asyncio.sleep(2.0 * self.shard_count, loop=self.loop)
 
-
         if self._fetch_offline:
             guilds = sorted(self._ready_state.guilds, key=lambda g: g.shard_id)