Update to 2.8.0
    
    - Translation updates from Weblate for ca, de, es, fr, nl, pl, uk
    - Update emoji annotations from CLDR
    - Update emoji data to Unicode 13.0 final
    - New option to choose whether spellchecking is done on the preedit
      and which colour to use
    - Spellcheck typed string in preedit and colour it if it is likely to be misspelled
    - More test cases for spellchecking and spellchecking suggestions
    - Restructure code for spellchecking and spellchecking suggestions