Add new publish overloads.

Build/MQTTnet.nuspec

@@ -18,6 +18,7 @@
 * [Client] Received messages are now processed completely in the worker thread without creating new Tasks.
 * [Client] Fixed wrong calculation for sending keep alive packets (thanks to @cstichlberger)
 * [Client] A clean disconnect (via DisconnectAsync) will no longer throw an exception.
+* [Client] Added new overloads for quick message publishing.
 * [ManagedClient] The managed client is moved to a separate nuget package.
 * [ManagedClient] Added an own message format with extended properties like ID (BREAKING CHANGE).
 * [ManagedClient] Fixed a loading issue of stored application messages (thanks to @JTrotta).

Source/MQTTnet/ApplicationMessagePublisherExtensions.cs

@@ -14,7 +14,7 @@ namespace MQTTnet
 
             foreach (var applicationMessage in applicationMessages)
             {
-                await publisher.PublishAsync(applicationMessage);
+                await publisher.PublishAsync(applicationMessage).ConfigureAwait(false);
             }
         }
 
@@ -25,7 +25,7 @@ namespace MQTTnet
 
             foreach (var applicationMessage in applicationMessages)
             {
-                await publisher.PublishAsync(applicationMessage);
+                await publisher.PublishAsync(applicationMessage).ConfigureAwait(false);
             }
         }
 
@@ -35,8 +35,7 @@ namespace MQTTnet
             if (topic == null) throw new ArgumentNullException(nameof(topic));
 
             return publisher.PublishAsync(builder => builder
-                .WithTopic(topic)
-            );
+                .WithTopic(topic));
         }
 
         public static Task PublishAsync(this IApplicationMessagePublisher publisher, string topic, string payload)
@@ -46,8 +45,7 @@ namespace MQTTnet
 
             return publisher.PublishAsync(builder => builder
                 .WithTopic(topic)
-                .WithPayload(payload)
-            );
+                .WithPayload(payload));
         }
 
         public static Task PublishAsync(this IApplicationMessagePublisher publisher, string topic, string payload, MqttQualityOfServiceLevel qualityOfServiceLevel)
@@ -55,11 +53,22 @@ namespace MQTTnet
             if (publisher == null) throw new ArgumentNullException(nameof(publisher));
             if (topic == null) throw new ArgumentNullException(nameof(topic));
 
+            return publisher.PublishAsync(builder => builder
+                .WithTopic(topic)
+                .WithPayload(payload)
+                .WithQualityOfServiceLevel(qualityOfServiceLevel));
+        }
+
+        public static Task PublishAsync(this IApplicationMessagePublisher publisher, string topic, string payload, MqttQualityOfServiceLevel qualityOfServiceLevel, bool retain)
+        {
+            if (publisher == null) throw new ArgumentNullException(nameof(publisher));
+            if (topic == null) throw new ArgumentNullException(nameof(topic));
+
             return publisher.PublishAsync(builder => builder
                 .WithTopic(topic)
                 .WithPayload(payload)
                 .WithQualityOfServiceLevel(qualityOfServiceLevel)
-            );
+                .WithRetainFlag(retain));
         }
 
         public static Task PublishAsync(this IApplicationMessagePublisher publisher, Func<MqttApplicationMessageBuilder, MqttApplicationMessageBuilder> builder)