Added !set nickname and !rename <user>

cogs/mod.py

@@ -81,6 +81,21 @@ class Mod:
         except Exception as e:
             print(e)
 
+    @commands.command(no_pm=True, pass_context=True)
+    @checks.admin_or_permissions(manage_nicknames=True)
+    async def rename(self, ctx, user : discord.Member, *, nickname):
+        """Changes user's nickname"""
+        nickname = nickname.strip()
+        if nickname != "":
+            try:
+                await self.bot.change_nickname(user, nickname)
+                await self.bot.say("Done.")
+            except discord.Forbidden:
+                await self.bot.say("I cannot do that, I lack the "
+                    "\"Manage Nicknames\" permission.")
+        else:
+            await send_cmd_help(ctx)
+
     @commands.group(pass_context=True, no_pm=True)
     @checks.mod_or_permissions(manage_messages=True)
     async def cleanup(self, ctx):