Removed unneeded usings from EditingCommandHandler.cs.

src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/Editing/EditingCommandHandler.cs

@@ -7,14 +7,12 @@ using System.Diagnostics;
 using System.Globalization;
 using System.IO;
 using System.Linq;
-using System.Net;
 using System.Runtime.InteropServices;
 using System.Windows;
 using System.Windows.Documents;
 using System.Windows.Input;
 using ICSharpCode.AvalonEdit.Document;
 using ICSharpCode.AvalonEdit.Highlighting;
-using ICSharpCode.AvalonEdit.Search;
 using ICSharpCode.AvalonEdit.Utils;
 using ICSharpCode.NRefactory.Editor;