As a first step in removing dive-site uuids, change the interface
of the get_dive_site_*() functions to return pointers instead
of uuids. This makes code a bit more complicated in places where
the uuid is extracted afterwards (needed NULL check). Nevertheless,
these places should disappear once pointers instead of uuids are
stored in the dive-structures.
Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>
68961a169e