Warning cleanup

- ignoring const
- declarations after statements
- some C files didnt include own headers (risking them getting out of sync)

Closes #1064

src/common/dbus/example.c

@@ -33,7 +33,7 @@ guint command_id;
 guint server_id;
 
 static void
-write_error (char *message,
+write_error (const char *message,
 	     GError **error)
 {
 	if (error == NULL || *error == NULL) {