Also enable chatstates when we receive them from our contacts.

It is tab-specific and off by default.

Thanks to Florob for the initial input

'nick' attribute has been introduced recently in the XEP. We still try the
'jid' attribute for backward compatibility. And also we don’t traceback
anymore if any of these fields is not present.

selected_row wasn’t reset

- log_errors option, true by default
- errors go in log_dir/errors.log (so $XDG_DATA_HOME/errors.log
    by default)

This should help a lot for debugging, and provide a way for people
to easily give debug traces without useless or personal infos.

A command argument can now be completed even if it isn’t the last
one in the input.

- Add a new method Input.new_completion
    Almost like the old auto_completion method, except taht it takes
    another argument: argument_position, which is the argument to be
    completed.
- Methods using the old completion method still work
- All completion methods in poezio now use the new one if necessary
- Further details can be found in the docstring of new_completion

also fix some typos in the comments, and a refresh issue with the input

Often, we search people but don’t actually want to open a tab with them
(maybe the users wants to talk to a specific resource, or see the contact’s
status, or things like that)
To open a tab to talk to this contact, the user just need to type Enter twice

Now each different match has a different priority.
It might need some tuning to have the desired result.

Archiving old logs is recommended before running this update,
just in case.

- now case-insensitive
- search in the bare jid instead of userpart only (and still in roster
  names)
- do not display groups when searching
- display offline contacts
- do not expand resources if they were before the search

- Add an option enable_carbons (defaults to false)
- Make a disco on non-roster entites to determine if the message
  commes from a muc private chat or not.

(also add colors to the /info command in MUCs)

(also add outcast to the completed roles)

(Except in MUC, where we check the User object for that)

(introduced in 686352d2, because a
nick bookmark can now be None)