With d1d0ad8d1a we set a timestamp to now
for all messages upon receival. Even if the original message didn't
contain any timestamp. So we can use the timestamp of retrieval for
logging and displaying and don't get them at each of those location
where they might differ.
This means that timestamp will never be NULL.
I don't see why we would want to check for the chat state only if
timestamp isn't there.
Probably because in XEP-0085 there is not timestamp defined.
So if it thats stanza it's not there and we can parse quicker, but there
is nothing forbidden it to be there.
Related to https://github.com/profanity-im/profanity/issues/1339
e41ae21bea