Safari-style bar behavior definer + delegate for creating a delegate chain

[VragonerDev]

With proposed delegate property in BLKFlexibleHeightBarBehaviorDefiner anyone can easily create delegate chains. E.g, when a UITableView sets its delegate to an instance of BLKFlexibleHeightBarBehaviorDefiner but also wants another object to act as the UITableViewDelegate you can write something like this:

myBar.behaviorDefiner.delegate = anotherObject;
self.tableView.delegate = (id<UITableViewDelegate>)myBar.behaviorDefiner;