public void insertNodeAt(Node insert, int index, double split) {
        addChild(insert, index, split);
        notifyStateChange();
    }
public void insertNodeAt ( Node insert , int index , double split ) { addChild ( insert , index , split ) ; notifyStateChange ( ) ; }
Inserts a node after (right of or bottom of) a given node by splitting the inserted
node with the given node.
@param insert    The node to be inserted.
@param index The index
@param split The split