For dives with many samples (i.e. logged dives), samples are merged.
I'm not exactly sure how this code works, but it does an
out-of-bound access in some cases. Avoid that by a simple
check.
That said, I wonder if this downsampling is a good idea. A user
reports that they have logged dives marked as manually added dives.
We now load them into edit mode, which means a significant loss
of information.
Perhaps we should consider dives with more than 100 samples as
non-manual dives?
Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>