Make a minor change to the headings.
Make a minor change to the play_again function

Before it was easy, in the heat of the game, to lose then
hit a key without meaning to and start a new game.
This will change it so that you have to hit a 'p' to play again.
Merge branch 'master' into development
The name in intro.py was wrong
Merge branch 'master' of https://github.com/MageJohn/Terminal_Worm