add two-user function

Idea: create a function that takes a date and a word to be guessed, w, as parameter and returns some string `s` a human cannot guess w from.
So a user A sends the string `s`, by whatever communication means (signal/ WhatsApp/ email …) and user B will paste `s` in the window form.
That way people could share Mastermind on desktops without worrying about remote access etc.