Added:
>A list that displays to the user what incorrect letters have already been guessed

Changed:
>is_correct() now only checks for correctness, which should have been it's job in the first
As such, I moved the functionality of updating the number of wrong guesses and the updating
of the blanks to their own functions.

Things to Add:
>Reading in a "Library"(.txt file) of words(perhaps phrases, too) and randomising which
word becomes the word to guess.