- 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/Common/Collections/IndexedCollection.cs

@@ -13,10 +13,8 @@ public class IndexedCollection<T> : IList<T> where T : class, IIndexed
     public int IndexOf(T item) => item.Index;
 
     public IndexedCollection()
-    {
-        Source = new();
-    }
-        
+        => Source = new();
+
     public IndexedCollection(IEnumerable<T> source)
     {
         lock (_locker)
@@ -125,7 +123,7 @@ public class IndexedCollection<T> : IList<T> where T : class, IIndexed
 
     public virtual T this[int index]
     {
-        get { return Source[index]; }
+        get => Source[index];
         set
         {
             lock (_locker)