The hash field in the picture-structure was in principle non-operational.
It was set on loading, but never actually changed. The authoritative
hash comes from the filename->hash map.
Therefore, make this explicit by removing the hash field from the
picture structure.
Instead of filling the picture structure on loading, add the
hash directly to the filename->hash map. This is done in the
register_hash() function, which does not overwrite old entries.
I.e. the local hash has priority over the save-file. This
policy might be refined in the future.
Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>
bdc470a80e