Bug in trie fixed (issue #220)

Signed-off-by: Martin Sustrik <sustrik@250bpm.com>
ignore cscope output
nn_hash_rehash()
Test whether ENOPROTOOPT is returned when nn_getsockopt is used to retrieve a subscription
Merge pull request #221 from pipul/dev

add new static func nn_hash_rehash()
Dong Fang added to the AUTHORS file

Signed-off-by: Martin Sustrik <sustrik@250bpm.com>