• Pure Perl: compose($not_canonically_reordered) works like that in XSUB,
  where an intervening character with higher combining class blocks
  the composition. (This change doesn't affect any normalization forms.)
  
• XSUB: NFD(), NFC(), NFKD(), NFC(), and FCC() are now in XSUB, then
  internal subroutine calls are avoided.
  
• The functions isComp_Ex(), isNFD_NO(), isNFC_NO(), isNFC_MAYBE(),
  isNFKD_NO(), isNFKC_NO(), and isNFKC_MAYBE() are documented.
  
• Tests are more amplified and documentations are more clarified.
  
• Makefile.PL: Change 26295 is incorporated.