backspace method
void
backspace()
Implementation
void backspace() {
if (_cursorX == 0 && currentLine.isWrapped) {
currentLine.isWrapped = false;
movePosition(_terminal.viewWidth - 1, -1);
} else if (_cursorX == _terminal.viewWidth) {
movePosition(-2, 0);
} else {
movePosition(-1, 0);
}
}