Be sure to check conditions in both directions.

Before, it was possible for e.g. a TOC only ticket to be returned when
the outward leg was that TOC but the return leg was another, or for
a station restriction to be missed in one direction.
Also check used operators are a subset of the restriction, not equality.
Basic Twitter card.
Not Via London extra stations.
Don't show Twitter button unless total fare present.
Fix op/route checking of single tickets.

Bug introduced recently, probably f964058 - we only want to check
both directions if it's a return ticket, the one direction otherwise.