Make style more airy; Dark mode real black; Recreate Icons

[schlagmichdoch]

• prevents automatic zooming on iOS
• adds gradients to dialogs, badges, x-peers, about page, wifi-tether icon
• switch to airy buttons
• make dark mode real black
• increase and conform border-radii
• replace icons to add gradient and conform transparent and maskable icons
• add overflowing shadows to send-text, receive-text and edit-paired-devices-dialogs