Add a ProtoTreeModel and use it in ProtoTree. This should make the UI
more responsive when we have lots of items in the tree.
Change-Id: Id26e6bcff84663867a8da17fd9ae86ff639b633f
Reviewed-on: https://code.wireshark.org/review/24774
Reviewed-by: Gerald Combs <gerald@wireshark.org>
Petri-Dish: Gerald Combs <gerald@wireshark.org>
Tested-by: Petri Dish Buildbot
Reviewed-by: Anders Broman <a.broman58@gmail.com>