The old code called directly into the DiveListModel. Instead,
send a signal and hook into the signal from the model. This
will allow us to remove the DiveListModel::instance() function.
This, in turn, is a step towards supporting multiple models
at the same time. However, currently the model manually
sets the hidden_by_filter flag in the core and therefore
only one active model is supported at a time.
Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>
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