Remove non-existant variable from debug statement

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

Add commented out options to subsurface.pro that enable debuging the planner.
Remove obsolete comment.
Clean up the selection tracking.
Force the re-sort of the divelist inside the reload instead of explicitly
calling it.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Don't crash if get_divenr is called with NULL argument

We shouldn't be doing that, but still, let's not crash.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
UI restructure: when adding a dive via displayed_dive it needs valid id

Otherwise we have one (or - yikes - more) dives with id 0.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Planner: initialize drop_stone_mode as false

Otherwise it could be used uninitialized when adding dives.

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