Core: pass dive, cylinder-id to fill_default_cylinder

The fill_default_cylinder() function calculated the MOD based
on the currently displayed dive. This does not seem to make sense:
- When importing dives, why would we care about the altitude and
  salinity of the currently displayed dive, possibly from a different
  trip.
- The planner is supposed to be thread-safe and should not touch
  global variables.

Of course this means that the importing-functions have to fill
out altitude and salinity before creating the default cylinder,
but this is their problem. For a freshly created dive they will
get the default values, which still seems less random than the
values from the displayed dive.

Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>

qt-models/cylindermodel.cpp

@@ -426,7 +426,7 @@ void CylindersModel::add()
 	}
 
 	int row = rows;
-	fill_default_cylinder(&displayed_dive.cylinder[row]);
+	fill_default_cylinder(&displayed_dive, row);
 	displayed_dive.cylinder[row].start = displayed_dive.cylinder[row].type.workingpressure;
 	displayed_dive.cylinder[row].manually_added = true;
 	displayed_dive.cylinder[row].cylinder_use = OC_GAS;