Only return 0..255 from main().

I think this may fix some bugs with windows exit codes being screwy.

changes/normalize_exit

+  o Minor features:
+    - Try harder to normalize the exit status of the Tor process to the
+      standard-provided range.

src/or/tor_main.c

@@ -27,6 +27,10 @@ int tor_main(int argc, char *argv[]);
 int
 main(int argc, char *argv[])
 {
-  return tor_main(argc, argv);
+  int r = tor_main(argc, argv);
+  if (r < 0 || r > 255)
+    return 1;
+  else
+    return r;
 }