Remove unused imports.

src/Renci.SshNet/Abstractions/DiagnosticAbstraction.cs

@@ -1,5 +1,4 @@
-using System;
-using System.Diagnostics;
+using System.Diagnostics;
 #if FEATURE_DIAGNOSTICS_TRACESOURCE
 using System.Threading;
 #endif // FEATURE_DIAGNOSTICS_TRACESOURCE

src/Renci.SshNet/AuthenticationMethod.cs

@@ -1,6 +1,5 @@
 using Renci.SshNet.Common;
 using System;
-using System.Collections.Generic;
 
 namespace Renci.SshNet
 {

src/Renci.SshNet/IAuthenticationMethod.cs

@@ -1,6 +1,4 @@
-using System.Collections.Generic;
-
-namespace Renci.SshNet
+namespace Renci.SshNet
 {
     /// <summary>
     /// Base interface for authentication of a session using a given method.

src/Renci.SshNet/Sftp/ISftpFileReader.cs

@@ -1,7 +1,4 @@
 using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Text;
 
 namespace Renci.SshNet.Sftp
 {