(U+6588): Use `<-denotational@usage' instead of `<-denotational' for

(U+6588): Use `<-denotational@usage' instead of `<-denotational' for
BUCS+5B78; add `ideographic-structure'; add `sound@ja/on'.
(U+5B66): Use `<-denotational@usage' instead of `<-denotational' for
BUCS+5B78; apply new conventions for glyph granularity.
(HNG-KHM0027-0): Use `<-denotational@usage' instead of
`<-denotational' for BUCS+5B78.
(U-0002D4D5): New character; use `<-denotational@usage' for BUCS+5B78.
(U-0002B76F): Use `<-denotational@usage' instead of `<-denotational'
for BUCS+5B78.
(U+5B78): Likewise.