Hangman game

Here, I provide a code for the hangman game that allows the following tricks:

1. A comprehensive English words dataset from NLTK
2. Only alphabet characters as user input are possible. No repetitions!
3. A simplistic graphical display of the hanging (dark!)
4. A total of 6 mistakes allowed --> can be made flexible upon following the steps described in the comment.
5. After the game is completed, a possibility to replay is offered.