update to 1.5.4
    
    - Accent insensitive matching
    - Update pl.po from zanata
    - Add cache for the suggestions from the hunspell dictionaries
    - Make Control+MouseButton1 remove the clicked candidate from
      the user database (was MouseButton2)
    - Change key binding for looking up related candidates
      from Alt+F12 to AltGr+F12
    - Change label of the emoji option to
      “☑ Unicode symbols and emoji predictions”