Add POC contrast and screen invert settings

source/Core/Drivers/OLED.hpp

@@ -62,6 +62,8 @@ public:
   static void setRotation(bool leftHanded); // Set the rotation for the screen
   // Get the current rotation of the LCD
   static bool    getRotation() { return inLeftHandedMode; }
+  static void    setContrast(uint8_t contrast);
+  static void    setInverseDisplay(bool inverted);
   static int16_t getCursorX() { return cursor_x; }
   static void    print(const char *string, FontStyle fontStyle); // Draw a string to the current location, with selected font
   static void    printWholeScreen(const char *string);