Remaining Possibilities functionality & hard mode

[vandanparmar]

Added functionality to show remaining possibilities after each guess - to support with creating good strategy and guiding guesses when training for wordle.

[vandanparmar]

Just reading other features, the available words list produced along with the list of possibilities would also support creation of hard mode (effectively either changing / restricting the answers and words lists based on the regex created)

[vandanparmar]

Closes octokatherine/word-master#6

[octokatherine]

someone else already implemented the hard/easy mode feature