unfinished_background implication removal and alias

BUR #17581 has been approved by @nonamethanks.

remove implication unfinished_background -> unfinished
create alias unfinished_background -> sketch_background

Aside from the fact this is an old cross-category implication, the background being "unfinished" does not make the entire post unfinished. post #6018010 and post #6303185 are finished pieces despite the background not being fully rendered.

The tag is also being misused on posts where the background wasn't drawn in full, but was still rendered to completion. post #4378242, post #4680779, post #4803754, post #5592541 etc. all feature backgrounds the artist obviously finished by intentionally only drawing part of them. To remove this ambiguity I've also included an alias to sketch_background, which also helps distance it from the unfinished tag in general.

I agree that unfinished_background isn't a very good tag, but I would split your two sets of examples. The first set fits under sketch_background but IMO the second set should instead be tagged something like "partial_background"

Super_Affection said:

I agree that unfinished_background isn't a very good tag, but I would split your two sets of examples. The first set fits under sketch_background but IMO the second set should instead be tagged something like "partial_background"

Last two of the second set are fading border.

The bulk update request #17581 (forum #244651) has been approved by @nonamethanks.