[idn] NamePrep with Japanese hiragana and katakana

[Hideyo Imazu <hideyo.imazu@msdw.com>]

Yoneya san's I-D (draft-ietf-idn-jpchar-00.txt) and his presentation on 
Wednesday ask NamePrep to add normalization rules (or table entries) 
for hiragana and katakana.  Namely rules for

HIRAGANA LETTER KA + KATAKANA-HIRAGANA VOICED SOUND MARK
-> HIRAGANA LETTER GA

and alike.
Because this kind of rules are not in NFKC despite there are rules such as

HIRAGANA LETTER KA + COMBINING KATAKANA-HIRAGANA VOICED SOUND MARK
-> HIRAGANA LETTER GA

in NFKC.

That said, instead of introducing many new rules into the normalization 
stage, introducing the following entries into the mapping table is reasonable.

KATAKANA-HIRAGANA VOICE SOUND MARK
-> COMBINING KATAKANA-HIRAGANA VOICED SOUND MARK

KATAKANA-HIRAGANA SEMI-VOICE SOUND MARK
-> COMBINING KATAKANA-HIRAGANA SEMI-VOICED SOUND MARK

Regards,
Hideyo Imazu.