Correctly parse Keyframe Presets with the new Spectator Keyframes from JSON

src/main/java/eu/crushedpixel/replaymod/holders/SpectatorData.java

@@ -14,7 +14,7 @@ import net.minecraft.entity.Entity;
 @EqualsAndHashCode(callSuper=true)
 public class SpectatorData extends AdvancedPosition {
 
-    private int spectatedEntityID;
+    private Integer spectatedEntityID;
 
     public SpectatorData(double x, double y, double z, double pitch, double yaw, double roll, int entityID) {
         super(x, y, z, pitch, yaw, roll);
@@ -30,6 +30,15 @@ public class SpectatorData extends AdvancedPosition {
         this.spectatedEntityID = e.getEntityId();
     }
 
+    /**
+     * @return itself if it's a valid SpectatorData object,
+     * otherwise a new AdvancedPosition object containing the same position data
+     */
+    public AdvancedPosition normalize() {
+        if(spectatedEntityID != null) return this;
+        return new AdvancedPosition(x, y, z, pitch, yaw, roll);
+    }
+
     @Override
     public SpectatorData newInstance() {
         return new SpectatorData();