Add mappings for Big5 code points.

Add mappings for Big5 code points.
(U+8ECF): Unify JC3-66ED.
(U+8ED1): Unify JC3-99B9.
(U+4848): Apply new conventions for glyph granularity; unify S-8138
and CB07274; add `<-original' for U+8F03; add H9-DABA.
(U+484E): Apply new conventions for glyph granularity.
(U-000282CF): Unify S-8133, H9-DB7C and CB07276; add `<-vulgar' for
U+8EEB.
(U+8EF0): Apply new conventions for glyph granularity.
(U+8EF9): Unify JC3-66EE.
(U+8EFA): Unify JC3-99BA.
(U+8F0F): Apply new conventions for glyph granularity.
(U+8F19): Use `->subsumptive'; add `<-vulgar' for U+8F12.
(U+8F21): Unify S-8185; add `<-original' for U+8F57.
(U+8F28): Apply new conventions for glyph granularity.
(U+8F2D): Unify S-8122 and CB00365; add `<-original' for U+8EDF.
(U+8F41): Apply new conventions for glyph granularity.
(U+8F58): Unify JC3-66FA.
(U+8F65): Apply new conventions for glyph granularity.