Sorts an array of UIViews or subclasses by tag.

SwiftArrayOfUIViewsSortInPlaceByTagExtension.swift

    extension Array where Element: UIView {
      
      /**
       Sorts an array of `UIView`s or subclasses by `tag`. For example, this is useful when working with `IBOutletCollection`s, whose order of elements can be changed when manipulating the views in Interface Builder. Just tag your views in Interface Builder and then call this method on your `IBOutletCollection`s in `viewDidLoad()`.
       - author: Scott Gardner
       - seealso:
       * [Source on GitHub](http://bit.ly/SortUIViewsInPlaceByTag)
       */
      mutating func sortUIViewsInPlaceByTag() {
        sort { (left: Element, right: Element) in
          left.tag < right.tag
        }
      }
      
    }