Add a DiveListNotifer::eventsChanged signal, which is emitted when
the events changed. This is very coarse, at it doesn't differentiate
between signal addition / editing / deletion. We might want to
be finer in the future.
Catch the signal in the profile-widget to replot the dive if this
is the currently displayed dive. Reuse the cylindersChanged() slot,
but rename it to the now more appropriate profileChanged().
Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>