The diveListNotifier.divesSelected() signal is used to inform the
models of a selection change. It sent the current dive as a second
parameter. This is redundant, because the only sender of the signal
sets current_dive just before sending the signal. Remove the
parameter, which appears to be an artifact.
Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>