Update locales-zh-TW.xml

I completed the translation and amended a few key terms to render the locale more user-friendly to the native speaker. 

General changes made are: 

1. Removal to the single / multiple differentiation as none exists for the Chinese language. 

2. For ordinals, the Chinese just prefix a 第 to the number. Since ordinals in cs: number are programmed as suffixes, there is no way to project Chinese ordinals in the locale. As such, I attempted a work-around with this: <term name="ordinal" suffix="第">""</term>. I wonder if this is legal under the program. 

3. Chinese has three ways to depict numbers. One is the Arabic numeral (1, 2, 3...); one is in Chinese characters (一、二、三...);  another is in "capital format", 大寫 daxie (壹、貳、參...). It would be nice if cs style can provide a way to inter-convert these number format. Meanwhile, I translate the long ordinal to 一、二、三 etc., with reference to the long and short month forms. But I doubt this will work as a work-around. 

4. Many terms in the original translation are never used in a published paper, which defeats the purpose of having a locale in the Chinese language. I render these terms to the more common form so as to conform to the norms in Chinese academia.