multiple fixes:
* wrong traversed va_list (original instead of the copy => segfault)
* UTF-8 converters were inverted (internal/external for non Unicode I/O)
* unsufficient buffers on conversions to UTF-8 were not growing up (do { continue; } while (FALSE); = 1 loop)
u_printf(...) => u_fprintf(ustdout, ...) to force a specific charset as ouput