Make filenames of images unique when saving

[Pino]

Right clicking save image as names images "Untitled" which forces users to rename them manually.
Some websites use the hash of the image as the filename which would solve this issue.

 

[BzzBzz]

Browser issue. Because blob doesn't inherit file name.

Devs actually can change it.
append("blob", blob, filename);

Won't help much since scanlators often don't name files properly.