Function init_logging 

pub fn init_logging(
    verbose: bool,
    quiet: bool,
    datadir: &Path,
    logfile: Option<PathBuf>,
    no_logfile: bool,
)

Sets up logging to the terminal (unless quiet) and to a debug log file.

The debug log file defaults to datadir/debug.log, but can be overridden with logfile, or disabled entirely with no_logfile.