v2.8

• adapt to recent update of unicode-letters.tex.
  Hangul syllables were of catcode 12 traditionally, and this is deeply
  interwined with Automatic Josa Selection. So, recent change of
  unicode-letters.tex, assigning catcode 11 to Hangul, is hereby
  reverted.
• allow font option only once, as per future release
  of fontspec