Split the process_imported_dives() function in two:
1) process_imported_dives() processes the dives and generates
a list of dives and trips to be added and removed.
2) add_imported_dives() calls process_imported_dives() and
does the actual removal / addition of dives and trips.
The goal is to split preparation and actual work, to
make dive import undo-able.
The code adds extra checks to never merge into the same
dive twice, as this would lead to a double-free() bug.
This should in principle never happen, as dives that
compare equal according to is_same_dive() are merged
in the imported-dives list, but perhaps in some pathologival
corner-cases is_same_dive() turns out to be non-transitive.
Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>
0249e12589