Dendrogram enhancements.
Dendrogram enhancements.

- Converted dendrogram to use tighter option processing

- Renamed newNodes to onNodeCreate

- Added onNodeDestroy option

- Fixed bug where reappearing nodes lose any event handlers they used to have,
  when they reappear

ecohealthalliance/tangelo,Kitware/tangelo,mathstuf/tangelo,mathstuf/tangelo,ecohealthalliance/tangelo,mathstuf/tangelo,ecohealthalliance/tangelo,Kitware/tangelo,Kitware/tangelo