v2.17.0

• [Added] node.addClass(), .removeClass(), and .toggleClass()
• [Added] ext-filter: matcher-callback for tree.filterNodes() may now return
  "branch" and "skip"
• [Added] ext-filter: new optionnodata allows to configure a status node for
  empty results
• [Added] digits argument to node.getIndexHier(separator, digits).
• [Added] tree option .tabindex, default is "0". Pass "" to resolve #577.
• [DEPRECATED] tree option .tabbable. Use .tabindex instead
• [Added] New option mode='firstChild' for node.moveTo()
• [Added] New option digits=<int> for node.getIndexHier()
• [Fixed] ext-filter: branch mode honors autoExpand: true
• [Fixed] #584: aria-labelledby ids not unique
• Update to jQuery UI 1.11.4

Commit details.