Optimized Images and updated phone and tablet

assets/images/amoled.png

assets/images/amoled@220.png

assets/images/amoled@266.png

assets/images/amoled@335.png

assets/images/amoled@352.png

assets/images/amoled@532.png

assets/images/phone.png

assets/images/phone@1000.png

assets/images/phone@1220.png

assets/images/phone@220.png

assets/images/phone@300.png

assets/images/phone@400.png

assets/images/phone@520.png

assets/images/phone@640.png

assets/images/phone@800.png

assets/images/phone@thumb.png

assets/images/quassel_dark.png

assets/images/quassel_dark@220.png

assets/images/quassel_dark@266.png

assets/images/quassel_dark@335.png