Allow for Export and Import of Custom Covers

[Animeboynz]

Resolves #16

[MajorTanya]

How does this work?

[Animeboynz]

What do you mean how does this work?

EDIT: Uses the manga url as a unique key to backup and restore covers stores into a gz (cus the manga id can change)
it also stores a protobuf inside the archive to link filenames to the urls

[Animeboynz]

Can someone rerun build cus I don't want any more force pushes showing xD

[AntsyLich]

A potential issue I see here is in case a manga url or source id (which should be part of backup. manga is unique by source and url) changes any old backup will have some redundancy

[Animeboynz]

What are the chances tho that 2 manga have the same URL

EDIT: I guess most sources now don't out the full URL in the URL field so it is possible

[Animeboynz]

Would you like me to add the sourceID to the protobuf too and use that while restoring?

[AntsyLich]

Yes

[Animeboynz]

I didn't bother retesting like I usually do with changes, but it a pretty minor change so fingers crossed

[MajorTanya]

I didn't bother retesting like I usually do with changes, but it a pretty minor change so fingers crossed

That's how I ended up having to make three follow-up PRs to #1748...