Refactor using Rankings to allow pluggable ranking for word pattern groups.

Printed results now annotate the pattern groups for each guess with all of the statistics used to rank guesses: number of groups, maximum group size, and variance in group size.

This release contains the following improvements.

• Better handling of input errors during interactive mode

• Words entered during interactive mode are checked for Wordle requirements

Show warning if using interactive mode while reading words from standard input.

Initial release