Log datapoints values in exact cron events

[nichokap]

Right now when logging of a datapoint in intervals is selected, the logging is happening on specific intervals starting from the enabling time and then counting.

Thus if the interval is set for example 10 minutes, I get logging at 14:32:28, 14:42:28, 14:52:28

It would be very handy to have to option to log in intervals that happen on specific cron events. Like every 10 minutes at 00 seconds in order to have loggings at 14:30:00, 14:40:00, 14:50:00.