Initial structure for supervisor-mode

The full process hierarchy isn't set up yet, but these changes
help prepare by doing two things:

- Add a -j option to enable supervisor-mode.  Currently, just a single
  "stem" process gets forked early on to be used as the basis for
  further forking into real cluster nodes.

- Separates the parsing of command-line options from their consumption.
  i.e. need to parse whether we're in -j supervisor-mode before
  modifying any global state since that would taint the "stem" process.
  The new intermediate structure containing the parsed options may
  also serve as a way to pass configuration info from "stem" to its
  descendent cluster node processes.

src/Pipe.cc

@@ -13,7 +13,11 @@ static void pipe_fail(int eno)
 	{
 	char tmp[256];
 	bro_strerror_r(eno, tmp, sizeof(tmp));
-	reporter->FatalError("Pipe failure: %s", tmp);
+
+	if ( reporter )
+		reporter->FatalError("Pipe failure: %s", tmp);
+	else
+		fprintf(stderr, "Pipe failure: %s", tmp);
 	}
 
 static void set_flags(int fd, int flags)