v0.2.0

Fixed

• The options closedIcon and openedIcon render a string as html instead of
  as text.

Changed

• Make rendering faster by using templates.
• The children of a closed folder are rendered when the folder is opened,
  instead of when the tree is rendered. onCreateLi is called for a node when
  it is rendered.
• The method getSelectedNode returns null instead of false.
• The method setState saves the state to storage when saveState is enabled.