Missing ViewUpdate for toggle arrows and node names

[mlototchi]

Nice work so far. Updating the view after adding/removing nodes works fine. Thanks for that, but there are still two little problems.

First: If you add a new node to a node, which have no child nodes yet (and no shown toggle arrow), the view does not update the appereance of the toggle arrows, so they are still invisible

Second: There is no view update, after changing the name of a node

[enisn]

I see,

IsLeaf and Name property should trigger PropertyChanged event. I'll handle it