Got rid of cancerous Cloneable interface and fixed possible NPE when cloning a Position Keyframe

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

@@ -1,11 +1,10 @@
 package eu.crushedpixel.replaymod.holders;
 
-public class Keyframe implements Cloneable {
+public class Keyframe {
 
     private int realTimestamp;
 
-    @Override
-    public Object clone() {
+    public Keyframe clone() {
         return new Keyframe(realTimestamp);
     }
 

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

@@ -8,7 +8,7 @@ public class MarkerKeyframe extends Keyframe {
     private String name;
 
     @Override
-    public Object clone() {
+    public Keyframe clone() {
         return new MarkerKeyframe(this.getPosition(), this.getRealTimestamp(), this.getName());
     }
 

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

@@ -8,8 +8,8 @@ public class PositionKeyframe extends Keyframe {
     private Integer spectatedEntityID = null;
 
     @Override
-    public Object clone() {
-        return new PositionKeyframe(this.getRealTimestamp(), this.getPosition(), this.getSpectatedEntityID());
+    public Keyframe clone() {
+        return new PositionKeyframe(getRealTimestamp(), position, spectatedEntityID);
     }
 
     public PositionKeyframe(int realTime, Position position) {
@@ -17,7 +17,7 @@ public class PositionKeyframe extends Keyframe {
         this.position = position;
     }
 
-    public PositionKeyframe(int realTime, Position position, int spectatedEntityID) {
+    public PositionKeyframe(int realTime, Position position, Integer spectatedEntityID) {
         super(realTime);
         this.position = position;
         this.spectatedEntityID = spectatedEntityID;

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

@@ -7,7 +7,7 @@ public class TimeKeyframe extends Keyframe {
     private final int timestamp;
 
     @Override
-    public Object clone() {
+    public Keyframe clone() {
         return new TimeKeyframe(this.getRealTimestamp(), this.getTimestamp());
     }