Add _powertime and _powercount to POWERMONITOR

I'm trying to do some tricky timing (a few milliseconds) with POWERMONITOR. It would be useful at have a more accurate time of the event than what I can get in POWERMONITOR's command. Milliseconds would be nice.

And it would be nice if POWERMONITOR's command could display the count without digging it out of the output of POWERMONITOR.