Merge: Liu Yan

I don't see any reason to assume these two are different people, but let me know if I overlooked something:
https://hkmdb.com/db/people/view.mhtml? ... ay_set=eng
https://hkmdb.com/db/people/view.mhtml? ... ay_set=eng
https://hkmdb.com/db/people/view.mhtml? ... ay_set=eng
https://hkmdb.com/db/people/view.mhtml? ... ay_set=eng