Display init zum Zweiten

chango to full Buffer Mode, remove picture loop,
because it's not worked.
look: https://github.com/olikraus/u8glib/wiki/tpictureloop

snprintf + public vars
- dispPowerSafe => true: PowerSafe Mode on
- dispLogo => true: showing Logo upper right corner
- dispContrast => possible to adjust the Display Contrast

change in date time, buffer deleted

Display-Constructor changed, reset goes to front

Arrow and Logo only shown, when production is on

Refactor OLEDDisplayClass to DisplayGraphicClass

include/Display_Graphic.h

@@ -0,0 +1,41 @@
+#ifndef Display_Graphic_H
+#define Display_Graphic_H
+
+#include <Arduino.h>
+#include <Hoymiles.h>
+#include <NetworkSettings.h>
+#include <U8g2lib.h>
+#include <map>
+#include <time.h>
+
+class DisplayGraphicClass {
+public:
+    DisplayGraphicClass();
+    ~DisplayGraphicClass();
+
+    void init(uint8_t type);
+    void loop();
+
+    bool dispPowerSafe = true;
+    bool dispLogo = true;
+    uint8_t dispContrast = 60;
+
+private:
+    void printText(const char* text, uint8_t line);
+
+    U8G2* _display;
+
+    uint8_t _mExtra;
+    uint8_t _display_type = 0;
+    uint16_t _dispX = 0;
+    uint16_t _dispY = 0;
+    uint16_t _period = 1000;
+    uint16_t _interval = 60000; // interval at which to power save (milliseconds)
+    uint32_t _lastPublish = 0;
+    uint32_t _previousMillis = 0;
+    char _fmtText[32];
+};
+
+extern DisplayGraphicClass Display;
+
+#endif