[FR]: "Fetch online metadata" when importing feeds shouldn't delete feeds

[Owyn]

Brief description of the feature request

I have tried a fresh rssguard install and & imported my feeds back,
I wanted my feed icons back so I kept "Fetch online metadata" checked

but the result was unexpected - it deleted my feeds (which it could not load)

So I tried again from the start and unchecked it - all my feeds got added BUT icons obviously didn't load for ANY feed

what I wanted:

• load icons for feeds it can,
• don't delete my feeds it can't load icons for
• (optional) update icons when fetching a feed automatically (else now I'd have to open edit window for each feed and click "fetch now" to get an icon)

[martinrotter]

Makes sense, will do eventually.