(U+72C3): Add `<-denotational@usage' for BUCS+72C3; add

(U+72C3): Add `<-denotational@usage' for BUCS+72C3; add
`sound@ja/on/{kan|go}'.
(JU+72C3): Unify DJT-07126; add `<-interchangeable' for IU+2062F and
JU+5FF8.
(UU+72C3): Add `ideographic-structure'.
(A-cgnU+7372): New abstract node.
(U+7372): Add `<-denotational' for A-cgnU+7372; add
`<-denotational@usage' for BUCS+7372; apply new conventions for glyph
granularity.
(HNG-KHM0091-0): Use A-cgnU+7372 instead of U+7372 as its mother.
(BUCS+72C3): New abstract node; unify A2-DJT-07126.
(BUCS+7372): New abstract node; unify A2-DJT-07241.