Inverted position shifting idle logo (#1484)

* Inverted idle logo

Back on white background start-up logo.
Inverted idle logo with random positioning.

* Idle Logo display default true

DISPLAY_IDLE_LOGO true as burn-in screens saver, especially fo the constant heading and line

* Display Brightness added

* SSD1306toMQTT / MQTTtoSSD1306

Additional "onstate" and "brightness" setting and regular display state reporting

Docs - separate Displays section

main/main.ino

@@ -1517,6 +1517,9 @@ void loop() {
 #  endif
 #  ifdef ZactuatorONOFF
         stateONOFFMeasures();
+#  endif
+#  ifdef ZdisplaySSD1306
+        stateSSD1306Display();
 #  endif
       }
 #endif