Core: unify insert_trip() and insert_trip_dont_merge()

There were two versions of the insert_trip() function: one
would merge trips if a trip with the same date already existed,
the other wouldn't. The latter was introduced with the dive-list
undo work.

The problem is that the "date" of a trip (i.e. the first dive)
seems ill-defined as this is a volatile value. Moreover in
the context of making dive-import undoable this is a very
dangerous notion, as the caller needs control over when the dives
are added to a trip.

Therefore, unify these two functions and never merge trips.
The decision on merging dives now has to made by the caller.
This will be implemented in a future commit.

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

core/load-git.c

@@ -1176,7 +1176,7 @@ static void finish_active_trip(void)
 
 	if (trip) {
 		active_trip = NULL;
-		insert_trip(&trip);
+		insert_trip(trip);
 	}
 }