--- NKF.nkf(opt, str)
    ʸ str ʸɤѴѴ̤ʸ֤ޤ

    opt ˤϡ
    nkf(1) [URL:http://rananim.ie.u-ryukyu.ac.jp/~kono/software.html] 
    Ʊޥɥ饤󥪥ץꤷޤʣꤹϡ
    NKF.nkf('-Se', str)  NKF.nkf('-S -e', str) ʤɤȤ
    ޤoptϡɬ '-' ǻϤʤФʤȤ
    Ƥ

    : 
      Υ᥽åɤ(nkf ޥɤǤ褦)MIME Base64 
      ǥɽǥեȤǥˤʤäƤޤư̵ˤ
       opt  '-m0' ޤ褦ˤƤ

