DnD and multiple old parents

[Sampas]

When DnDing multiple objects, data.rslt.op in move_node() and is the same for every moved node, although they can be selected from different branches. There should be old parent for each moved object. The problem occurs also in check_move. Using _get_parent(o) in move_node() returns the new parent, so the only workaround is to use before-function, but I see this is impractical.