add field log_level

data/settings.yaml

@@ -1,6 +1,7 @@
 system:
     log_file: "data/log_8700W_8ms" # filename without extension  [replay only]
                                    #   use / as path delimiter, even on Windows 
+    log_level:      0              # log level, 0=quiet
     time_lapse:    12              # relative replay speed
     sim_time:  1000.0              # simulation time             [sim only]
     segments:       6              # number of tether segments