decode_utf16

# File lib/rexml/encodings/UTF-16.rb, line 18
    def decode_utf16(str)
      str = str[2..-1] if /^\3376\3377/ =~ str
      array_enc=str.unpack('C*')
      array_utf8 = []
      0.step(array_enc.size-1, 2){|i|
        array_utf8 << (array_enc.at(i+1) + array_enc.at(i)*0x100)
      }
      array_utf8.pack('U*')
    end