clean up: remove unused namespaces

Resources/Libraries/DotNetZip/Source/Zlib/ParallelDeflateOutputStream.cs

@@ -27,7 +27,6 @@
 using System;
 using System.Collections.Generic;
 using System.Threading;
-using Ionic.Zlib;
 using System.IO;
 
 

Resources/Libraries/DotNetZip/Source/Zlib/Tree.cs

@@ -60,9 +60,6 @@
 //
 // -----------------------------------------------------------------------
 
-
-using System;
-
 namespace Ionic.Zlib
 {
     sealed class Tree

Resources/Libraries/DotNetZip/Source/Zlib/Zlib.cs

@@ -88,8 +88,7 @@
 
 
 
-using System;
-using Interop=System.Runtime.InteropServices;
+using Interop = System.Runtime.InteropServices;
 
 namespace Ionic.Zlib
 {

Resources/Libraries/DotNetZip/Source/Zlib/ZlibConstants.cs

@@ -60,9 +60,6 @@
 //
 // -----------------------------------------------------------------------
 
-
-using System;
-
 namespace Ionic.Zlib
 {
     /// <summary>