Add Material You

[Myzel394]

Material You (https://material.io/blog/announcing-material-you) is Google's new beautiful design for Android apps. It features a special color scheme and bigger buttons. The color scheme changes dynamically based on the current background image. For simple QR I think we could start by adapting to the new color scheme, as this is probably the most difficult part. I took a quick look at the code, it seems to be a hybrid web app, doesn't it? I'm not sure how to access the colors there, maybe there's a library for that available. For Flutter there's for example <gonna_insert_this_when_im_at_my_pc> available.

Thanks for Simple QR, I love it :)