Add abc.GuildChannel.clone to clone a channel with another name.

Fixes #2093

discord/abc.py

@@ -603,6 +603,46 @@ class GuildChannel:
         else:
             raise InvalidArgument('Invalid overwrite type provided.')
 
+    async def _clone_impl(self, base_attrs, *, name=None, reason=None):
+        base_attrs['permission_overwrites'] = [
+            x._asdict() for x in self._overwrites
+        ]
+        base_attrs['parent_id'] = self.category_id
+        base_attrs['name'] = name or self.name
+        guild_id = self.guild.id
+        cls = self.__class__
+        data = await self._state.http.create_channel(guild_id, self._type, reason=reason, **base_attrs)
+        obj = cls(state=self._state, guild=self.guild, data=data)
+
+        # temporarily add it to the cache
+        self.guild._channels[obj.id] = obj
+        return obj
+
+    async def clone(self, *, name=None, reason=None):
+        """|coro|
+
+        Clones this channel. This creates a channel with the same properties
+        as this channel.
+
+        .. versionadded:: 1.1.0
+
+        Parameters
+        ------------
+        name: Optional[:class:`str`]
+            The name of the new channel. If not provided, defaults to this
+            channel name.
+        reason: Optional[:class:`str`]
+            The reason for cloning this channel. Shows up on the audit log.
+
+        Raises
+        -------
+        Forbidden
+            You do not have the proper permissions to create this channel.
+        HTTPException
+            Creating the channel failed.
+        """
+        raise NotImplementedError
+
     async def create_invite(self, *, reason=None, **fields):
         """|coro|