If we get a private message from a user in a MUC profanity shows this
like:
`profanity@roomsASDF.dismail.de/Martin: Hi`
This was so far logged at:
`~/.local/share/profanity/chatlogs/my-account-at-server/profanity_at_rooms.dismail.de/2019_09_04.log` as:
```
10:48:13 - profanity@rooms.dismail.de: Hi
```
So the nickname was not saved anywhere. This is due to us not knowing
whether we got a regular message from user@server.org/resource or a MUC
PM from room@server.org/user.
We now check for `<x xmlns='http://jabber.org/protocol/muc#user' />` and
add the resourcepart to the logging if we get it.
The file will be created at
`~/.local/share/profanity/chatlogs/my-account-at-server/profanity_at_rooms.dismail.de_nick` and look like:
```
23:59:43 - nick: Hi
```
Fix https://github.com/profanity-im/profanity/issues/1184
Probably missing copy of body to plain in carbon and privmessage.
Only covers the incoming message path because goal is OMEMO decryption
of untrusted message.
Cover some of the log functions but not all.
