Enable cloning of QCMPFileHeader.

src/main/java/azgracompress/fileformat/QCMPFileHeader.java

@@ -8,7 +8,7 @@ import java.io.DataInputStream;
 import java.io.DataOutputStream;
 import java.io.IOException;
 
-public class QCMPFileHeader {
+public class QCMPFileHeader implements Cloneable {
     public static final int BASE_QCMP_HEADER_SIZE = 23;
     public static final String QCMP_MAGIC_VALUE = "QCMPFILE";
 
@@ -57,6 +57,19 @@ public class QCMPFileHeader {
         return true;
     }
 
+    @Override
+    protected Object clone() throws CloneNotSupportedException {
+        return super.clone();
+    }
+
+    public QCMPFileHeader copyOf() {
+        try {
+            return (QCMPFileHeader) this.clone();
+        } catch (CloneNotSupportedException e) {
+            return null;
+        }
+    }
+
     public void writeHeader(DataOutputStream outputStream) throws IOException {
         outputStream.writeBytes(QCMP_MAGIC_VALUE);