Language-specific font name should be used if there is one matching system locale

Some TTF fonts contain language-specific font names (e.g. CJK fonts: MingLiU / SimSun / MS Gothic / Gulim), if there exists one matching the system locale, that name should be used instead.

Also needs to handle situations like zh-HK -> zh-TW (like how resources should be handled, but that's another issue somewhere else).