Increase sending period to 30 seconds
Add lost packets to S message
Handle the case here read() gets a 0 len
Add radio sending retries.  Needed now that RF24 doesn't have them
Harden against accidentally setting node address to 0
Initial implemntation of system config k/K messages
Reliably fetch system config from parent
Changes needed for relay nodes to deal with problems found in deployment
Account for an 'invalid' radio
Add eeprom_update_block for older avrlibc's which are missing it