Removed unused directives

DocX/DocX.cs

 using System.IO;
 using System.Text.RegularExpressions;
 using System.IO.Packaging;
-using System.Security.Principal;
-using System.Reflection;
-using System.IO.Compression;
 using System.Security.Cryptography;
 
 namespace Novacode

DocX/Headers.cs

-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Text;
-
-namespace Novacode
+namespace Novacode
 {
     public class Headers
     {

DocX/Image.cs

 using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Text;
-using System.Xml.Linq;
 using System.IO.Packaging;
 using System.IO;
-using System.Drawing;
-using System.Drawing.Imaging;
 
 namespace Novacode
 {