converted FIXME into NOTE

prescaler and loopdelay values from flocklab config.ini file are now used for datatrace postprocessing
made piecewise regression work with arbitrary cpuSpeed
removed code for offset correction based on reset

node_id removed from timesync and error logs, and also log an error if an observer is unreachable or fails to start a test

added byte rate based offset correction for old linux platform

use sleep_overhead value from trace file to add platform dependent time correction factor to improve datatrace offset