Add arduino EEPROMEx library
Add getSlitPosition function for Tetris class
Add support for persistance of nominal slit positions across startups.
Update AccelStepper library from 1.27->1.30
Bugfixes and reliability to EEPROMEx library.
EEPROM storage of slit poritions and motor positions guarded by CRC16 with EEPROMEx now working.
Reenable monitoring of locking nut.