Added check (& skipping) of the utf-8 byte order mark (0xEF BB BF) at the beginning of the file

include/flatbuffers/idl.h

@@ -444,6 +444,7 @@ private:
   FLATBUFFERS_CHECKED_ERROR Error(const std::string &msg);
   FLATBUFFERS_CHECKED_ERROR ParseHexNum(int nibbles, int64_t *val);
   FLATBUFFERS_CHECKED_ERROR Next();
+  FLATBUFFERS_CHECKED_ERROR SkipByteOrderMark();
   bool Is(int t);
   FLATBUFFERS_CHECKED_ERROR Expect(int t);
   std::string TokenToStringId(int t);