purely a clone of 'zh.py'. rename to 'zh-tw.py' for more precise
fix 'langcode' from 'zh-cn' to 'zh-tw'.
This is a specific language file for 'zh-cn'. The former 'zh.py' should be renamed to 'zh-tw.py'. web2py is a good project, thank you very much. I wish I could do something for you all.