Uses the additions to the UI tree-view API from the previous commit to
enable drag & drop of asset catalogs. The catalogs will be moved in the
tree including children.
A remaining issue is that a catalog with children will always be
collapsed when dropping. I need to find a way to fix that in the
tree-view API.
There are a few improvements I can think of for the tree-item drag &
drop support, but time for these is too short. These can be done as
normal cleanups at some point.
aae5f15238