Dive pictures: remove hashes

In the last commits, the canonical-to-local filename map was made
independent from the image hashes and the location of moved images
was based on filename not hashes. The hashes are now in principle
unused (except for conversion of old-style local filename lookups).

Therefore, remove the hashes in this commit. This makes addition
of images distinctly faster.

Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>

core/parse-xml.c

@@ -1221,7 +1221,7 @@ static void try_to_fill_dive(struct dive *dive, const char *name, char *buf)
 	if (MATCH("gps.picture", gps_picture_location, cur_picture))
 		return;
 	if (MATCH("hash.picture", utf8_string, &hash)) {
-		register_hash(cur_picture->filename, hash);
+		/* Legacy -> ignore. */
 		free(hash);
 		return;
 	}