Writes a log message to the console or an ACSII file.
output - identifier for output method. Options are 'hush' to suppress the output, or an integer file identifier. report_string - a character string. A newline symbol at the end of the string is not necessary - it is added by the function. depth - the amount of top level stack to ignore, default is 0. close_file - is a logical true or false, to close the output file if one was previously defined (see notes below).
For the output to a file, output is a file identifier inherited from optim_tols.m (input as string of file-name to optim_tols.m), or set it to 1 (for standard output, the screen) or 2 (standard error).