rotateUp

    void rotateUp( Node* p )    // WIP
    {
        Node* A = p;
        Node* B = A.parent;
        Node* G = B.parent;
        // Which side is A
        Side  S = A.side;

        // Fix Grand parent
        if( G !is null )
        {
            G.child[ B.side ] = A;
        } else {
            root = A;
        }

        // Fix parent links
        A.parent = B.parent;
        B.parent = A;

        // Then children
        B.child[ S] = A.child[!S];
        A.child[!S] = B;

        // Fix sides
        A.side = B.side;
        B.side = !S;
        auto two = A.child[!S];
        if( two !is null )
            two.side = S;
    }