bug#3179: Entering Chinese "zero": add U+3007

[jidanni]

With locale zh_TW.UTF-8 and toggle-input-method, we can type
Possible completion and corresponding characters are:
 ling2:(1/6) 1.零 2.玲 3.靈 4.鈴 5.齡 6.陵 7.凌 8.菱 9.聆 0.羚...
       (6/6) 1.駖 2.蕶 3.爧 4.堎 5.○

Useful when one wants to type the year 2003:
公文都有「二○○三年」，非「二零零三年」。

But in http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=427519
MH> You probably want "〇" (U+3007) instead of "○" (U+25CB)
So maybe add that in addition (not instead).

(And ０, 0...? nah.)