Tag Alias: duck_(princess_tutu) -> ahiru

Aliasing duck_(princess_tutu) -> ahiru.
Aliasing mythos -> mytho.
Aliasing siegfried_(princess_tutu) -> mytho.
Aliasing mr._cat -> neko-sensei.

Reason:
- EN -> JP
- "Full" name -> Common name (see here)
- True name -> Common name (and here)
- EN -> JP (also recognized in Japanese materials)

Also, Autor's name is given in these materials as AOTOA. So, however that would be handled.

(bumped from url edits; IGNORE IT!)

Were any of these actually in use besides mythos previously? If not, I don't think we need to worry about it.

I manually moved mythos to mytho.