reverseIndex method

void reverseIndex()

https://terminalguide.namepad.de/seq/a_esc_cm/

Implementation

void reverseIndex() {
  if (isInVerticalMargin) {
    if (_cursorY == _marginTop) {
      scrollDown(1);
    } else {
      moveCursorY(-1);
    }
  } else {
    moveCursorY(-1);
  }
}