Replace screenshots

assets/images/gruvbox_light@thumb.jpg

assets/images/quassel_dark.png

assets/images/quassel_dark@220.png

assets/images/quassel_dark@266.png

assets/images/quassel_dark@335.png

assets/images/quassel_dark@352.png

assets/images/quassel_dark@532.png

assets/images/quassel_dark@thumb.jpg

assets/images/quassel_light.png

assets/images/quassel_light@220.png

assets/images/quassel_light@266.png

assets/images/quassel_light@335.png

assets/images/quassel_light@352.png

assets/images/quassel_light@532.png

assets/images/quassel_light@thumb.jpg

assets/images/solarized_dark.png

assets/images/solarized_dark@220.png

assets/images/solarized_dark@266.png

assets/images/solarized_dark@335.png

assets/images/solarized_dark@352.png