Adding a few options to the ASCII writer.

module LogAscii;

export {
	# Output everything to stdout rather than into files. This is primarily
	# for testing purposes.
	const output_to_stdout = F &redef;

	# The separator between fields.
	const separator = "\t" &redef;

	# True to include a header line with column names.
	const include_header = T &redef;
}

src/LogWriter.h

@@ -3,7 +3,9 @@
 //
 // Note than classes derived from LogWriter must be fully thread-safe and not
 // use any non-safe Bro functionality (which is almost all ...). In
-// particular, do not use fmt() but LogWriter::Fmt()!.
+// particular, do not use fmt() but LogWriter::Fmt()!. The one exception is
+// the constructor: that is guaranteed to be executed inside the main thread
+// and it can thus access in particular global script variables.
 
 #ifndef LOGWRITER_H
 #define LOGWRITER_H