Replace UUIDs from LocationInformationModel and fix the fallout.
Notably, replace the UUID "column" by a DIVESITE "column".
Getting pointers through Qt's QVariant is horrible, we'll have
to think about a better solution.
RECENTLY_ADDED_DIVESITE now defines to a special pointer to
struct dive_site (defined as ~0).
This fixes an interesting logic bug:
The old code checked the uuid of the LocationInformationModel (currUuid)
for the value "1", which corresponded to RECENTLY_ADDED_DIVESITE.
If equal, currType would be set to NEW_DIVE_SITE. Later, _currType_
was compared against _RECENTLY_ADDED_DIVESITE_. This would only work
because NEW_DIVE_SITE and RECENTLY_ADDED_DIVESITE both were defined
as 1.
Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>