Added proper .equals and hashCode methods for Keyframes

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

@@ -1,5 +1,7 @@
 package eu.crushedpixel.replaymod.holders;
 
+import org.apache.commons.lang3.builder.HashCodeBuilder;
+
 public class PositionKeyframe extends Keyframe {
 
     private final Position position;
@@ -12,4 +14,20 @@ public class PositionKeyframe extends Keyframe {
     public Position getPosition() {
         return position;
     }
+
+    @Override
+    public boolean equals(Object o2) {
+        if(o2 == null) return false;
+        if(!(o2 instanceof PositionKeyframe)) return false;
+        PositionKeyframe kf = (PositionKeyframe)o2;
+        return hashCode() == kf.hashCode();
+    }
+
+    @Override
+    public int hashCode() {
+        return new HashCodeBuilder(17, 37)
+                .append(getPosition())
+                .append(getRealTimestamp())
+                .toHashCode();
+    }
 }