Online exchange of a nested simulation via loading *[ir].par files
[sim, out] = ld_nested_exchffile(sim, events, compresult, slot, fname, simnest_name)
NOTE: May delay realtime behaviour - use during a separated asynchronous nested simulation
compresult - signal - 0: Do nothing, 1: unload schematic and load new (replace), 2: just unload
slot - signal (unused by now; set to 2)
fname - the filename without ".[ir]par"-ending
simnest_name - the string which referes to the nested simulation (as given to "ld_simnest2")