Add glyph-images of HNG-KHM.

Add glyph-images of HNG-KHM.
(U+5999): Separate UU+5999.
(UU+5999): Add `=>ucs@iwds-1'.
(U+5999-itaiji-001): New character to integrate HNG-KHI0334-0 and
HNG-KHM0273-0; add `<-denotational' for U+5999.
(U+59DF): Separate UU+59DF.
(UU+59DF): Add `=>ucs@iwds-1'.
(HNG-KHM0024-0): New character; add `<-denotational' for U+59DF.
(U+5A01): Apply new conventions for glyph granularity; separate
UU+5A01.
(UU+5A01): Add `=>ucs@iwds-1'.
(HNG-KHM0340-0): New character; add `<-denotational' for U+5A01.
(U+5A11): Separate UU+5A11.
(UU+5A11): Add `=>ucs@iwds-1'.
(HNG-KHI0336-0): Use `<-denotational' instead of `<-subsumptive' for
U+5A11.