IEV data treatment: 151-15-01

@ronaldtse This is really inconsistent… https://gist.github.com/skalee/e281031db37a1a08941f04ec1a7721af And I'm pretty sure I'll find even more when I improve the SQL query.

"AC" term is quite interesting — qualifier in English or Polish whereas abbreviation in Portuguese or Spanish:

```
151-15-01 ar تيار متردد (متناوب)
151-15-01 de Wechselstrom… in Zusammensetzungen
151-15-01 en AC qualifier
151-15-01 es AC, calificativo
151-15-01 fi AC
151-15-01 fr AC qualificatif
151-15-01 it AC; c.a.; corrente alternata
151-15-01 ja 交流
151-15-01 ko 교류 수식어
151-15-01 pl AC (kwalifikator)
151-15-01 pt CA (abreviatura)
151-15-01 ru АС, обозначение
151-15-01 sr AC квалификатор
151-15-01 sv vs-
151-15-01 zh 交流
```

_Originally posted by @skalee in https://github.com/glossarist/iev-data/issues/94#issuecomment-765680069_