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
b3ed213668