IKEv1 XAUTH: Added ability to configure XAUTH+PSK. Added task to handle XAUTH requests. Modified task_manager_v1 to enable it to initiate new tasks immediately after finishing a response.

src/libstrongswan/credentials/auth_cfg.h

@@ -42,6 +42,8 @@ enum auth_class_t {
 	AUTH_CLASS_PSK = 2,
 	/** authentication using EAP */
 	AUTH_CLASS_EAP = 3,
+	/** authentication using pre-shared secrets in combination with XAuth */
+	AUTH_CLASS_XAUTH_PSK = 4,
 };
 
 /**