feather_hair_ornament -> hair_feathers

BUR #5392 has been rejected.

create alias feather_hair_ornament -> hair_feathers
create implication hair_feathers -> hair_ornament

We don't need both tags, and they're identical in meaning as far as I can tell: a feather added to a character's hair. I just wrote a wiki for hair_feathers accordingly.

Alternatively, the alias should go the other way, because feather_hair_ornament is more consistent with the other *_hair_ornament tags, and to be less easily confused with feather_hair. However, we already have hair_flower, and hair_feathers is older and more frequently used than feather_hair_ornament. I don't particularly care which one we use, but there should only be one tag.

I would argue for the reverse alias to avoid miss tags for feather hair.

BUR #5398 has been approved by @evazion.

create alias head_feathers -> feather_hair

While we're at it, these two are also identical: feathers coming out of the head/hair of bird_girls, actually connected to their body rather than added as a hair_ornament.
There was a small minority of posts under head_feathers that seemed more like hair_ornaments, so I just retagged them as hair_feathers

The bulk update request #5398 (forum #185189) has been approved by @evazion.

The bulk update request #5392 (forum #185154) has been rejected by @evazion.

BUR #5459 has been approved by @evazion.

create alias hair_feathers -> feather_hair_ornament
create implication feather_hair_ornament -> hair_ornament

Reversing it for better consistency and less confusion. Although now we have both feather hair and feather hair ornament, which is probably just confusing in a different way.

The bulk update request #5459 (forum #185618) has been approved by @evazion.