- 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.

Also add an override parameter to new_completion so that the
completion does not care if the list matches the previous input
or not.

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

This will only work if the message ids are the same across all
participants…

Added a configuration option and some theme variables.

If a tab with the given fulljid is not found, then a new tab
will be opened, even if we are in discussion with the bare jid.

(why did that even work before)

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

(since we can’t do anything about them anyway)

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

For example 😆

it might be a little slower than before (more checks)

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.