Merge pull request #12 from zonama-sekot/ship-fighter

Ship moves, invaders everywhere!
Add more interfaces: Dimensional, Positionable and Pane
Use new interfaces in all classes
Make invader detect collisions with the ship and stop the game
Merge pull request #18 from zonama-sekot/invaders-kill-ship

Detect collisions between the invaders and the ship
Merge branch 'ship-fighter' into test

* ship-fighter:
  Position missile in the center of the ship
  Add image, dimensions and speed of the missile
  Fix line endings and whitespace
  Added new Missile.class and SpacePanel.class edited. nut still not working. Try to fix the problem. Missiles should fly up!
Make use of IDimensional and IPositionable in Missile

Fix initialization of missile x,y because of the IPositionable and MovablePanel.
Fix line endings