always dump config when saving
add ability to set millisecond timer (for debug)
schedule all config changes, rather than just some
use magic values to indicate valid config
arrange to hit timer wraparound after just 5 minutes

...rather than after 24 days
V command for dumping eeprom config from monitor
add debug support for timer rollover

print timestamp in several more places, and fix the monitor
command for resetting the tick counter to just before the
wraparound.
fix check_timer() to handle timer wraparound correctly