Yomitan: add search keys for old character forms (kyūjitai)

[stephenmk]

https://www.asahi-net.or.jp/~ax2s-kmtn/ref/old_chara.html

Yomitan supports a new definition format that I can use to add search keys for old character variations of search keys. I can use the table of characters in the link above to determine which variations to add.

For example, this will allow users to search for the words 欠陷, 缺陷, or 缺陥 and be redirected automatically to 欠陥.