forked from: Now you too can understand how Arena Shooting in 100 Lines works

UPDATE: Now the code is fully commented, I have finished the remaining parts.
by the way it is nice to fit so much functionality into 100 lines
Hats off keim_at_Si!
What I have done to the code:
- renaming variables/functions
- explaining constructs
- moving functions outside the main constructor
What I haven't done:
- modifying the internal logic
- refactoring. (I am trying to perserve the original forms) 
Arena Shooting in 100 Lines.
Movement;[Arrow key], Shot;[Ctrl], Slow & Head fix;[Shift]