current_dive is the selected dive, and displayed_dive is the one we are
currently drawing. They are quite often the same one, but not in the
case of adding a dive for example.
This fixes potential null pointer dereferences in the case of a blank
divelist, and makes sure we use the correct data in the case of adding
and planning dives.
Signed-off-by: Anton Lundin <glance@acc.umu.se>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
8e5eb71e0b