Translate more strings into Traditional Chinese and make some locale behavior update

There are 4 things I have done:
1. Update translation of article speed/unnecessary-paints
2. Make watermark link to root with current locale you use, without this update, the watermark always link to 'en' now.
3. There are some strings have hosted by po file but not been wrapped by ```{% trans "string" %}``` on the feature HTML files. So make the strings can be localized.
4. Translate more strings into Traditional Chinese