Add option to disable link previews

[lifenautjoe]

Some people might find link previews annoying. Let's provide an in-app way to disable them.

[lifenautjoe]

Perhaps split them into

Preview images

Preview links

[lifenautjoe]

It should also be disabled when the data settings are set to medium or low. Expanding images and GIFs is resourceful.

[lifenautjoe]

preview images should probably be "Always" "Never" "Wifi only"

[jari604]

The link preview option has already been added. The separate options for photos has not been added yet.