Disambiguating Zangetsu

BUR #26341 has been approved by @nonamethanks.

rename zangetsu -> zangetsu_(bleach)

There are plenty of other things called Zangetsu, meaning any of them left unqualified is ambiguous.

AngryZapdos said:

There are plenty of other things called Zangetsu, meaning any of them left unqualified is ambiguous.

Heck, there are even multiple Bleach characters called Zangetsu! But spoilers.

The bulk update request #26341 (forum #280972) has been approved by @nonamethanks.