Add current time and adjusted time to gui when adjusting dive's timestamp

This patch adds the current dive time and the adjusted time to the time
shift window. I added a function to dive.c to get the timestamp of the
first selected dive.

This will view the time of the first selected dive only even when multi
dives are selected but it does change the times for multiple dives
properly.

Signed-off-by: Gehad elrobey <gehadelrobey@gmail.com>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Make pp graphs visible at startup according to settings

Changeset a90818671 introduces a small inconvenience. The pp graphs at
startup are not shown according to the visibility settings. Requiring to
toggle the icons to show the desired pp graph.

Trivial fix.

Signed-off-by: Jan Mulder <jlmulder@planet.nl>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Fix system default font handling

We didn't care about system default fonts and sizes, we just used the Qt
default font.

Due to how QFont is constructed, there was need to split font and font
size.

Signed-off-by: Anton Lundin <glance@acc.umu.se>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>