v0.1.1

Changelog

• Improved serialization of the tree.
• Added more unit and regression tests.
• Getting the children of a node returns a Vec<Q> which is basically a list of node ids rather than actual node elements.
• Changed some of the functions in the API to take references instead of actual values. Including
  • Tree<Q, T>::get_node(&self, node_id: &Q)
  • Tree<Q, T>::remove_node(&self, node_id: &Q, strategy: NodeRemovalStrategy)
  • Tree<Q, T>::get_subtree(&self, node_id: &Q, generations: Option<i32>)
  • Tree<Q, T>::add_subtree(&self, node_id: &Q, subtree: SubTree<Q, T>)