Add SteamAuthentication to handle new Steam login flow sessions

Samples/1a.Authentication/Program.cs

@@ -4,7 +4,7 @@
 
 if ( args.Length < 2 )
 {
-    Console.WriteLine( "Sample1: No username and password specified!" );
+    Console.Error.WriteLine( "Sample1a: No username and password specified!" );
     return;
 }
 
@@ -60,7 +60,7 @@ async void OnConnected( SteamClient.ConnectedCallback callback )
     } );
 
     // Starting polling Steam for authentication response
-    var pollResponse = await authSession.StartPolling();
+    var pollResponse = await authSession.PollingWaitForResultAsync();
 
     // Logon to Steam with the access token we have received
     // Note that we are using RefreshToken for logging on here

Samples/1b.QrCodeAuthentication/Program.cs

@@ -55,7 +55,7 @@ async void OnConnected( SteamClient.ConnectedCallback callback )
 
     // Starting polling Steam for authentication response
     // This response is later used to logon to Steam after connecting
-    var pollResponse = await authSession.StartPolling();
+    var pollResponse = await authSession.PollingWaitForResultAsync();
 
     Console.WriteLine( $"Logging in as '{pollResponse.AccountName}'..." );
 

SteamKit2/SteamKit2/Steam/Handlers/SteamAuthentication/AuthenticationException.cs

@@ -5,12 +5,20 @@ namespace SteamKit2
     /// <summary>
     /// Thrown when <see cref="SteamAuthentication"/> fails to authenticate.
     /// </summary>
-    public class AuthenticationException : Exception
+    [Serializable]
+    public sealed class AuthenticationException : Exception
     {
         /// <summary>
         /// Gets the result of the authentication request.
         /// </summary>
-        public EResult Result { get; private set; }
+        public EResult Result { get; }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="AuthenticationException"/> class.
+        /// </summary>
+        public AuthenticationException()
+        { 
+        }
 
         /// <summary>
         /// Initializes a new instance of the <see cref="AuthenticationException"/> class.

SteamKit2/SteamKit2/Steam/Handlers/SteamAuthentication/IAuthenticator.cs

@@ -4,7 +4,7 @@
 namespace SteamKit2
 {
     /// <summary>
-    /// 
+    /// Represents an authenticator to be used with <see cref="SteamAuthentication"/>.
     /// </summary>
     public interface IAuthenticator
     {
@@ -13,22 +13,22 @@ public interface IAuthenticator
         /// </summary>
         /// <param name="previousCodeWasIncorrect">True when previously provided code was incorrect.</param>
         /// <returns>The 2-factor auth code used to login. This is the code that can be received from the authenticator app.</returns>
-        public Task<string> ProvideDeviceCode( bool previousCodeWasIncorrect );
+        public Task<string> GetDeviceCodeAsync( bool previousCodeWasIncorrect );
 
         /// <summary>
         /// This method is called when the account being logged into uses Steam Guard email authentication. This code is sent to the user's email.
         /// </summary>
         /// <param name="email">The email address that the Steam Guard email was sent to.</param>
         /// <param name="previousCodeWasIncorrect">True when previously provided code was incorrect.</param>
         /// <returns>The Steam Guard auth code used to login.</returns>
-        public Task<string> ProvideEmailCode( string email, bool previousCodeWasIncorrect );
+        public Task<string> GetEmailCodeAsync( string email, bool previousCodeWasIncorrect );
 
         /// <summary>
         /// This method is called when the account being logged has the Steam Mobile App and accepts authentication notification prompts.
         ///
         /// Return false if you want to fallback to entering a code instead.
         /// </summary>
         /// <returns>Return true to poll until the authentication is accepted, return false to fallback to entering a code.</returns>
-        public Task<bool> AcceptDeviceConfirmation();
+        public Task<bool> AcceptDeviceConfirmationAsync();
     }
 }