Fixed file name validation of lcg-plot. Added process niceness control,
improved determinism of inter-trial sleep by using time.sleep and
reducing calculations between trials in lcg-stimulus.
Added last option so that plot can plot only the last N files.
Changed way kernel protocol looks for file and for the gaussian noise. Added KERNEL protocol variables to lcg-env.
Changed lcg-stimulus so that verbose option controls what is written to the terminal.