readerzoomin: add zoom mode translation, simplify zoom mode validation
readerzoomin: add zoom mode translation, simplify zoom mode validation
koreader/koreader,poire-z/koreader,Frenzie/koreader,koreader/koreader,poire-z/koreader,NiLuJe/koreader,NiLuJe/koreader,Frenzie/koreader