update to 1.5.8
    
    - Pull translations from Zanata (uk and fr updated)
    - Match many more Unicode characters in the emoji matcher
    - Make it possible to match Unicode characters by typing the hexadecimal code point
    - If one tries to set a non-existing input method, don’t crash,
      only print an error in the debug log
    - Add key and mouse bindings for “Off the record” mode to README