• Convert file input to slurping+splitting.
  
  • This provides a significant (3m05s instead of over 4m)
    speed boost.
    
• Some other optimisations.
  
• Add Games::Solitaire::Verify::Column->append_cards for faster
  appending.
  
• Add Games::Solitaire::Verify::Column->popN for popping multiple
  cards from the top.
  
• Add Games::Solitaire::Verify::Card->get_ranks_strings().