Selection Edit: first pass

Let user select an item from the root Roster edit screen, and open a Selection Edit screen.
For now, Symbols and etc aren't in place for editing, so this will be a view-only screen.
Although editing isn't possible yet, adding the UI to edit ints, dropdowns, etc, could still be created.
Selection Edit should allow a Selection to be ...selected, if it has subselections, and show those subselections (ie, the SelectionEdit should have some recursion to it)