Redesign cards

Cards are now structured differently. There are active, previous and
next cards. This is how a life of a card now looks like:

next -> active -> <user resolves> -> prevous -> invisible -> cleanup
Split all less files
Add meta tag to prevent scaling on mobile devices
Clean LESS files
Disable virtual keyboard

Virtual keyboard has lower priority than the rest of the code and it's
therefore disabled. It'll be enabled again when the right time comes.
Move hint into cards

Hints, or descriptions, are now inside cards.
Merge branch 'paper-card-design'