added Bird.class with its own attributes

src/Bird.java

+import bagel.Image;
+
+public class Bird {
+    /* positive means moving up, negative means moving down */
+    public double velocity;
+    private static int frameCounterSinceStart = 0;
+
+    public Image birdWingUp = new Image("res/birdWingUp.png");
+    public Image birdWingDown = new Image("res/birdWingDown.png");
+
+    public final double acceleration = 0.4;
+    public final double terminalVelocity = 10;
+
+    public final double x = 200;
+    public double y = 350;
+
+    public void Bird() {
+    }
+
+    public void Render() {
+
+        if(this.frameCounterSinceStart % 10 == 0) {
+            this.birdWingUp.draw(this.x, this.y); /* repeat every 10 frames */
+        }
+        else {
+            this.birdWingDown.draw(this.x, this.y);
+        }
+        this.frameCounterSinceStart++;
+    }
+}
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