Also enable chatstates when we receive them from our contacts.

It is tab-specific and off by default.

(also includes silent modification of the hash already
in the config)

See https://github.com/afflux/pure-python-otr/issues/47

(should prevent some conditions leading to config
corruption happenning when poezio cannot write anymore)

- do not save the config (only for roster and stuff)
- do not except that resetting the curses state will work everytime

TODO (eventually):
    - correct words when using “word*” or “*word” using levenshtein distance
    - allow regular expressions for replacement

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.

Like /link 1:10 to open the last 10 links

Fixes #2130

Noticeable changes:

- The input "view" is smarter, it always move to a decent position so we can
  see enough text around the cursor.
- The cursor goes at the end of the input when pasting some long text
- The formatting chars (^C and o, b, a, 1, 2, 3 etc) are now visible in the
  input. This makes it a lot easier to know where these special characters
  are, to change them and efficiently edit our text (we just lose a little,
  on the cosmetic side, but who cares)
- The code is actually a lot simpler in the functions to move the cursor,
  insert/delete chars: we do not have to deal with special cases where the
  formatting characters are actually composed of two chars.

fixes #2183

(the tab-specific commands were executed first, but their help wasn’t
given first)

selected_row wasn’t reset