add hook for INT_TICKSECOND which is called once per second
update pmu handling, separate out single alert and add state/hooks for managing ADC-based edge triggering
change pin check interval to 1Hz
revert back to no default sleep delay
make flat compass default on v7, and 10 second pin check interval
Revert to 10 second checks on V8, 1 second checks on V7
fix 0 sleep time and simplify powerdown code