Renaming danmaku

Posted under Tags

BUR #11018 has been approved by @nonamethanks.

create alias niconico_comments -> danmaku_comments
create alias bilibili_danmu -> danmaku_comments

Going with the more generic name as Bilibili now also has the danmaku function, and the art may not necessarily refer to Niconico. Going with "bilibili danmu" for the alias since Bilibili also has the traditional scroll-down comment function. Also Qualifying the danmaku attack in games like Touhou to give a clearer distinction.