upgrade flutil (flu_msleep() and flu_system())
use flu_msleep()
bring back n sleep(1) after dispatcher fork
implement n_helpers dump_execution_state()
wait at most 3 seconds in n specs, closes gh-3
free res in dump_execution_state()
rename dump_execution_state() to dump_execution()
rework the 'trace' inst (for the new double 'v')
introduce instr tree() and child_count() helpers