- More code cleanup and codestyle updates

- Fixed some possible nullref exceptions
- Methods signatures now have up to 3 parameters before breakaing down each parameter in a separate line
- Method invocations have the same rule, except the first parameter will be in the same line as the invocation to prevent some ugliness when passing lambas as arguments
- Applied many more codestyles
- Extensions folder fully reformatted

src/NadekoBot/Services/Impl/StartingGuildsListService.cs

@@ -8,9 +8,7 @@ public class StartingGuildsService : IEnumerable<ulong>, INService
     private readonly ImmutableList<ulong> _guilds;
 
     public StartingGuildsService(DiscordSocketClient client)
-    {
-        this._guilds = client.Guilds.Select(x => x.Id).ToImmutableList();
-    }
+        => this._guilds = client.Guilds.Select(x => x.Id).ToImmutableList();
 
     public IEnumerator<ulong> GetEnumerator() =>
         _guilds.GetEnumerator();