This decouples the cyclic refreshing of reachability from the manual reading of the LQI tables: Changes the reachable refresh to only poll once a minute, cycling devices that need polling. Also checking for reachable will now only read the LQI table. Also removes the coordinator node from the cyclic checks. In case a manual refresh is triggered, both LQI and RTG tables will be read of all non-sleepy nodes, including the coordinator and without any delays in between polls.