cpoll: added Stream::getBufferedOutput()
cpoll: moved BufferedOutput
cpoll: flush StreamWriter when destructor is called
cpoll: don't set this->handle in Handle::init() if the given handle is negative
cpoll: fix hardcoded buffer size in StreamReader
cpoll: fixed MemoryStream::write(). previous version was totally broken.
cpoll: added Stream::readToEnd()
cpoll: added MemoryStream::data() and MemoryStream::length()
cpoll: added MemoryStream::flush()