selectBetween(startNode, endNode) {
        this.batch();

        let node = startNode.nextVisibleNode();
        while (node.id !== endNode.id) {
            node.select();

            node = node.nextVisibleNode();
        }

        this.end();

        return this;
    }
Select all nodes between a start and end node.
Starting node must have a higher index path so we can work down to endNode.

@param {TreeNode} startNode Starting node
@param {TreeNode} endNode Ending node
@return {Tree} Tree instance.