1.8: Plain Sort

• No key caching
• Similar to common sorts with a code block
• Good for small sort sets as there is no caching
• Pass 'plain' option to make_sorter

  	sub {
  
  		sort {
  		do{ my( $left, $right ) = map { $_->[0] } $a, $b;
  			$left cmp $right }
  			||
  		do{ my( $left, $right ) = map { $_->[1] } $a, $b;
  			$left cmp $right }
  
  		} @_  ;
  	}