Feature request: openAll() and closeAll()

[nutmix]

When you have a large data set, you have to start with all nodes except children of root closed.
i.e. use autoOpen(false)

However, searching when autoOpen is false is bad - it doesnt show the filtered nodes, only their parents, and you still have to open each parent in turn to find what you are looking for.

Also, in the UI, it would be great to give the user a button to "Open All" and "Close All".

This would work really well with the ability to toggle "autoOpen" This can only be set when you create the tree, you cant seem to change it after.