Change reporter messages to more reliably print to stderr.

Moved this functionality to be internal instead of in the script-layer
event handlers.  The issue with the later is that bad things can happen
between the time a reporter event handler is dispatched and the time it
is executed, and if bro crashes in that time, the message may never be
seen/logged.

Addressed #930 (and revisits #836).

src/main.cc

@@ -824,6 +824,8 @@ int main(int argc, char** argv)
 		exit(1);
 		}
 
+	reporter->InitOptions();
+
 	init_general_global_var();
 
 	if ( user_pcap_filter )