decoding: fix decoding of large events like nostr reports (William Casarin)

test: add test for failing nostr report event (William Casarin)

search: find_event_with_subid (William Casarin)

pushed to damus:refs/heads/master

http://git.jb55.com/damus/commit/0178478199706ac1921bda0815697590391322b9.html