Add a Remove view animation completion callback

[Wuou]

Hello, your library is great to use and greatly reduces the effort of scrolling vertical layouts. This code is elegant, clean, and organized.👍🏻 When the view is removed and the animation is finished, I need to do something, and I think it makes sense to add an animation completion callback, like this: open func removeRow(index: Int, animated: Bool = false, completion: (() -> Void)? = nil)