Reefnet Sensus dataloggers report in mbar (CSV import)

Sensus dataloggers report depth in (absolute) millibar. This simple
fix corrects the CSV import. The depth is now computed correctly.

Signed-off-by: Jan Mulder <jlmulder@planet.nl>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Correctly handle dive selection after editing dives

It's a tricky problem as we need to remember this across a divelist sort
(as the user might have edited the date / time). The old code made not one
but two incorrect assumptions.
a) it assumed that the added or edited (but previously manually added)
dive was the last one in the dive list (clearly wrong when adding a dive
that has an earlier date)
b) it ignored the fact that refreshDisplay() would select the top dive in
the list if no dive was selected

This patch addresses both of them and makes the code easier to understand.

Fixes #480

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