Mqtt client receives and sends messages from MQTT broker

• Receives messages in the background when the application is not running
• Works with multiple servers and has message filtering by topic
• Keeps the history of sent messages and allows them to be re-sent
• Generates notifications
• Highlights messages with the same topics
• Can group messages with one topic. Only the last message will be displayed

Setting:
1. To add a server, click "+" in the settings window
2. Specify the path to the broker, for example: "tcp: //192.168.1.1"
3. Specify the port: "1883"
4. If the broker is password protected, then specify "Login" and "Password"
5. Enter topic and press "+". The topic is specified in the format "name / #", where # is any port
6. Turn on "Notifications" to display pop-up messages from the broker
7. Press the "Restart" button to restart the service

Sending a message:
1. Select the type of delivery:
a) "QoS 0" - the publisher sends a message to the broker once and does not wait for confirmation from him
b) "QoS 1" - the message will definitely be delivered to the broker, but there is a possibility of duplicate messages from the publisher. The subscriber can receive multiple copies of the message
c) "QoS 2" - at this level, delivery of messages to the subscriber is guaranteed and possible duplication of sent messages is excluded. Each message has a unique identifier
2. Enter a topic, for example: "t10 / cmd"
3. Enter a message, for example: "{port: 10, value: 1}"
4. Click "Submit"
The message can be selected previously sent by clicking on it.

Filtering messages:
1. Enter a topic separated by a space, for example "t14 t15"
2. The data will be immediately filtered
3. If you press the "Filter" button, the filtering will be disabled.