add card view mode

[rafaelcastrocouto]

I can add this swith basic css and save the chosen option in localstorage with a few lines of js

[plebe1us]

It would be nice to have, especially on mobile, but it's not as easy as it sounds. Seedit (or old reddit) isn't designed for card mode, so the post cards would need a lot of design changes for card mode to work:

• a light border around each post or at least a <hr> between each post;
• text contents need to appear on top of the media, not below, without the existing expando border and sliced to a max length;
• expand buttons should be hidden when on card mode;
• max height and max width for all expanded media, which must use the API's calculated linkHeight and linkWidth or the feed virtualization will stutter (we use Virtuoso)
• leave the small thumbnails for webpage links