Dive add: remove duplicate code

This is already done when we create the fake dive.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Dive planner: remember the selection before new dives get handled

On an empty dive list we would remember the new dive (which gets
auto-selected since it's the only dive) and then crash when we try to
restore that selection after cancel (in which case that new dive is gone).

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Dive planner: remove the fake dive earlier on cancel

This way it's already gone from the dive list before it gets reprocessed.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Try to clear out the profile when dive list is empty

This only partially works. If I start from an empty dive list, plan a
dive, then abort, there are still leftovers in the profile widget.
Hitting Ctrl-W clears that out. But it just runs the same cleanUpEmpty()
again...

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Minor cleanup

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>