Refactor & Bug Fix

`game.ts`
 - fixed score on new game

`Obstacle.ts`
 - made distanceBetweenPipes and startX public
 - moved initialization of distanceBetweenPipes and startX to game.setupGame()

`Pipe.ts`
 - created move() method to move the pipe

 `Raspberry.ts`
  - added constant variables for Raspberry size

frontend/model/Pipe.ts

@@ -37,6 +37,14 @@ class Pipe extends Entity implements Collidable {
         pop();
     }
 
+    /**
+     * Moves the pipe to the lift with the given speed
+     * @param speed how fast the pipe moves
+     */
+    public move(speed: number): void {
+        this.position.x -= speed;
+    }
+
     /**
      * Determines when the pipe is colliding with another entity
      * @param o other entity