Fix to save loglevel from serial console.

Previously there was no way to make the log level stick if it was set on the console. Now it persists to EEPROM.
Added proper initialization of preference handler for Brusa DMC5.

A prior change to code had changed the way that the preference handler is
initialized and this change never made it to the Brusa DMC code.
Fixed up copy/paste errors in sys_io
Fix to allow systype and log level to be set and persisted properly.
Merge remote-tracking branch 'upstream/ArduinoDue' into ArduinoDue