Calibration of braille tray door-X

Calibration of braille tray door is included from V5 Beta firmware 2017-12-22. This function is designed to be used by Index distributor and they can get the pin code used for accessing the "protected service" menu from support@indexbraille.com. 

• Menu/ protected service/ calibration of braille tray door. The short cut to start this function is "hold DOOR key pressed until it beeps".
• Run calibration of braille tray door. The message "calibrated value is ###" verify successfully completed calibration.