Fix inverted horizontal scrolling

Fixes #15
Multiple fixes

* Remove test code (partially commented out) to draw a single ship #4
* Add position parameter to SetupShip in GameObject #4
* Draw player ship (potentially twice) #4
  - Player ship not drawn for me without explicitly drawing cameraTarget
    in executeDraw (GameObject)
  - Was (probably) still drawn for Anders without it
* Add slow turn (default) and fast turn (with shift key) #5
* Assign often used method returns to variables in Human #5
* Draw debug position text only for the player ship #3
  - Round the positions to the nearest integer
* Remove unused draw method in Unit #3
* Fix super fast rotation (Treat the percentage as a percentage) #2