[Feature Request] Improve print / println for special character like umlauts

[bitboy85]

• Arduino board: Arduino Nano

• Arduino IDE version (found in Arduino -> About Arduino menu): 1.8.10

Currently its not handy using special characters with the display print method.

Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);
//Works fine:
display.print("Hello World!");
//shows garbage
display.print("Ä Ü Ö ä ü ö ß");
// Is possible with
display.print("\224 \201 \204");  //Using octal ASCII
//or
display.print("\x94 \x81");  //Using hex ASCII
//or
display.write(0x94);

It would be very user friendly if umlauts in strings would be automatically converted by the library as it reads much better and is more easy to use.

[mzero]

Please see my extensive comment in #190
Adafruit_GFX (and by extension Adafruit_SSD1306) does bring characters with umlauts. The Issue is that you are using the wrong encoding.