Fix longstanding bug in MBI and Sailfish firmware: Z Hold setting was being read from EEPROM *after* being pushed down to the stepper code level.  As a result, the default of OFF was enacted.  However, printing from SD card or built-in script would repush the correct value down before starting the print.  Printing from USB would not.  But cancelling the print over USB would then push it down as part of the soft reset and thus subsequent prints over USB would be okay.  Note that the lack of Z Hold would only show up during types of pauses in the print as the code tries to leave the Z stepper engaged as much as possible regardless of the Z Hold setting.  That's a difference from the handling for Cupcakes in which the setting must be honored all the time.