Added Read1Write2Test, and AbstractMqttTest.

- all tests have fail-fast-behaviour if mqtt broker is not connected
- added some documentation on how to create new test cases
- Base: Fixed logging of writes to output actual values of terminal and topic

src/main/jastadd/backend/Generation.jadd

@@ -208,7 +208,9 @@ aspect AspectGeneration {
       .append(writeMethod()).append("() {\n");
     if (loggingEnabledForWrites) {
       sb.append(ind(2)).append("System.out.println(\"[Write] ").append(getToken().getName())
-        .append(" = \" + ").append(lastValue()).append(" + \" -> ").append(writeTopic()).append("\");\n");
+        .append(" = \" + ")
+        .append("get").append(getToken().getName()).append("() + \" -> \" + ")
+        .append(writeTopic()).append(");\n");
     }
     // _mqttUpdater().publish(${writeTopic()}, ${lastValue()});
     sb.append(ind(2)).append(mqttUpdaterAttribute()).append("().publish(")