Adds delimiter to serial output.

measurement_main.py

             #    .replace(";;OK", ";")
             #    .replace(";;", ";")
             #)
-            write_to_file(output_file, response + "\n")
+            write_to_file(output_file, response + ";;;\n")
     except:
         if not ser.is_open:
             print_message("Serial port is closed. Exit monitoring thread.")