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)

This way, if the MUC service decides to give us an other nick than the one
we asked it works properly.

- Do not crash because of low disk space
- Notify the user whenever it happens
- A few functions now return a boolean instead of nothing
- Config.silent_set is Config.set_and_save without toggle and returning
  strings. It is used whenever we don’t need set_and_save
- Config.set_and_save now returns a tuple (that can be passed directly
  to core.information())

TODO: display the precise error to the user (instead of “unable to…”)

- The input is split in two parts: on the left is what the user enters,
    on the right is the first match (the right part has a different
    color)
- Start and cancel a search with ^R
- Validate a search with enter, then press another time enter to send

- CommandInput and MessageInput now inherit from the HistoryInput class
  and share some methods

- Refactor the message handlers to be more readable
- Add a group_corrections tab-specific option (#2229)
- Fix issues with /correct in private tabs and conversation tabs