ytaudio: add [p]summon to join VC; revert tts join change

Add a summon command (alias ytjoin) that joins the caller's voice
channel, replacing the old Audio-cog summon. _ensure_connected now
moves the bot with Player.move_to when it is already in a different
channel. Revert the ttstoy tts join back to the simple connect.

ytaudio/ytaudio.py

@@ -323,9 +323,17 @@ class YTAudio(commands.Cog):
         if ctx.author.voice is None or ctx.author.voice.channel is None:
             await ctx.send("You need to be in a voice channel.")
             return False
+        target = ctx.author.voice.channel
         me_voice = ctx.guild.me.voice
-        if me_voice is None or me_voice.channel != ctx.author.voice.channel:
-            await lavalink.connect(ctx.author.voice.channel)
+        if me_voice is None or me_voice.channel is None:
+            await lavalink.connect(target)
+        elif me_voice.channel.id != target.id:
+            # Already connected to a different channel: move instead of reconnecting.
+            try:
+                player = lavalink.get_player(ctx.guild.id)
+                await player.move_to(target)
+            except Exception:
+                await lavalink.connect(target)
         return True
 
     # ------------------------------------------------------------------
@@ -441,12 +449,12 @@ class YTAudio(commands.Cog):
             pass
         await ctx.send("Volume set to {}.".format(level))
 
-    @commands.command(name="ytjoin")
+    @commands.command(name="summon", aliases=["ytjoin"])
     @commands.guild_only()
     async def join(self, ctx: commands.Context):
-        """Join your voice channel."""
+        """Summon the bot to your voice channel."""
         if await self._ensure_connected(ctx):
-            await ctx.send("Joined.")
+            await ctx.send("Joined your voice channel.")
 
     @commands.command(name="ytleave", aliases=["ytdc"])
     @commands.guild_only()