Massive cleanup

- Removed GuildConfigs repository, moved to extensions
- Moved StreamSettings extension to GuildConfig extensions
- namespace NadekoBot.Core has been simplified to NadekoBot in many places (more to come)
- Replaced some raw delete queries with simple linqtodb queries

src/NadekoBot/Modules/Music/Common/ITrackCacher.cs

@@ -3,7 +3,7 @@ using System;
 using System.Collections.Generic;
 using System.Threading.Tasks;
 
-namespace NadekoBot.Core.Modules.Music
+namespace NadekoBot.Modules.Music
 {
     public interface ITrackCacher
     {