All tests up to date and working

- AircraftTest now doesn't need testOutOfAirspaceBounds()
+ wrote test method for testIsAt
+ also updated instance for a new Score
ScoreTest again updated instance for new score
+ needed to include GameWindow class in order to initiate the scoring
system
+ also needed to initiate the graphics in order to run the test
- In demo class added a return Game method specific for testing
+ needed it in order to get the GameWindow for the ScoringTest
- Airport test had to initialise the graphics in order for it to work
+ updated methods that needed extra parameters