Add glyph-images of HNG-KHM.

Add glyph-images of HNG-KHM.
(U+4F0E): Separate UU+4F0E.
(U+4F0E-var-001): New character; add `<-denotational' for U+4F0E; add
HNG-KHM0185-0.
(HNG-KHI0239-0): Use U+4F0E-var-001 instead of U+4F0E as the mother.
(U+4F5B): Separate UU+4F5B.
(U+4F5B-itaiji-002): New character; add `<-denotational' for U+4F5B;
add HNG-KHM0186-0.
(HNG-KHI0242-0): Use U+4F5B-itaiji-002 instead of U+4F5B as the
mother.
(A-HDU+512A): Unify U+512A; use `=ucs' instead of
`=>ucs@hanyo-denshi'.
(A-J0-4D25): Separate U+512A; unify A-UU+512A; add `=>ucs@iwds-1'.
(HNG-KHM0005-0): New character; add `<-denotational' for U+512A.