Normalize variant characters to orthodox characters

[dahlia]

Sometimes Korean texts contain some variants characters (異體字; e.g., 俗字, 略字), or directly quote Simplified Chinese characters (簡化字) or Japanese shinjitai (新字體). As dictionaries tend to index words in a single writing system, these characters need to be normalized to orthodox characters (康熙字典體) so that they are able to match to dictionary indices.

E.g., 毛泽东 or 毛沢東 → 毛澤東.