Both loadFromDive() callers were clearing the model before
calling loadFromDive(). Move the clearing into that function
since it makes no sense to load into a non-cleared model.
Apparently this changes the way that no-cylinder dives are
treated and the code in ProfileWidget2::repositionDiveHandlers()
must now explicitly check for that condition.
Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>