Set TODO mark to rewrite mg_upload (#180)

src/civetweb.c

@@ -7695,6 +7695,7 @@ static uint32_t get_remote_ip(const struct mg_connection *conn)
 
 int mg_upload(struct mg_connection *conn, const char *destination_dir)
 {
+    /* TODO (high): completely rewrite this function. See issue #180. */
 	/* TODO (mid): set a timeout */
 	const char *content_type_header, *boundary_start, *sc;
 	char *s;