Fix addStop to work as slot again

In order to call this as slot it needs to have defaults for all arguments.
So we need to change the gasmix into a pointer - which is actually better
as this allows to easily pass a NULL pointer when we want to continue to
use the previous gas.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Optionally strip diveplan to bare minimum

There are new check-boxes to modify the look of the diveplan in the notes.

The old behaviour appears with "verbatim display", others are shorter,
runtimes, stoplengths and transitions being optional.  Also round to full
meters and minutes to remove optical clutter.

To be done: Remember these setting in the config.

Signed-off-by: Robert C. Helling <helling@atdotde.de>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Planner: warn about high pO2

If the user entered part of the plan exceeds a pO2 of 1.6, include a
warning about that in the notes.

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