Provision for 'historical versions' of piapro media

[riipah]

Moved from VocaDB/vocadb#503

Example: https://piapro.jp/ex_content/history_list/0on9/1 (https://vocadb.net/S/7319):

• https://piapro.jp/t/0on9/20091108085115 1925
• https://piapro.jp/t/0on9/20091108085816 1925 Karaoke
• https://piapro.jp/t/0on9 1925 Karaoke w/o Chorus

[szc126]

I found another (スラッシュミクさん 1988 Edition / CD Edition / niconico Edition, based on the description), but the feature also appears to have been scrapped; the links given above do not work anymore.