* added streaming i/o for scripting, and a byteutil.get_size function
* added i/o stream class, also added named pipes support on lua side via ffi
* added constant file.named_pipes_prefix
* added buffered and yield modes for io_stream
* added new time function for work with UTC - utc_time, utc_offset, local_time
* docs updated
* constant pid moved to os.pid
* now gmtime_s and localtime_s used only in windows
