Reads a UTF-8 string from the stream.

        @rtype: C{unicode}

def read_utf8_string(self, length):
        """
        Reads a UTF-8 string from the stream.

        @rtype: C{unicode}
        """
        s = struct.unpack("%s%ds" % (self.endian, length), self.read(length))[0]

        return s.decode('utf-8')