Update zh_CN.lang

木榴油 is a variant form for 木馏油, so it's unnecessary to change it.
Anyway, it's also unnecessary to change back it. 
And if anyone else is interested in Chinese translation for Railcraft, it's better to using English punctuation in order to unify the existing text.
Merge pull request #201 from crafteverywhere/patch-4

Update zh_CN.lang