Add test generators for saddle-points say scrabble-score secret-handshake series sieve space-age square-root state-of-tic-tac-toe sublist sum-of-multiples swift-scheduling

Add test generators for saddle-points say scrabble-score secret-handshake series sieve space-age square-root state-of-tic-tac-toe sublist sum-of-multiples swift-scheduling #670