support for on()/off() in LCD

Support to switch on and off the LCD.

{{{

!c++

void on()
{
display();
backlight();
}
void off()
{
noBacklight();
noDisplay();
}
}}}

Closes #20 - remove wait 1us during interrupt masking in loadSR. Not needed. Closes #19 - Added support for on/off commands Closes #18 - Set backlight initial state during initialization to off. Closes #17 - New SR3W class. Added documentation for new class Move some methods for the public interface of the LCD class to private, since they should never be called by the user.

→ c5879ff3f2e5