Add support for new changelog index element

Client side for https://gitlab.com/fdroid/fdroidserver/issues/63.

https://gitlab.com/fdroid/fdroidclient/merge_requests/93 should include this, or the changelog support should come once the MR is merged.

Reassigned to @NicoAlt

Status changed to reopened

FYI: this is also in one of the first issues - Issue #9 (closed). Don't care if we close one or the other, or neither until implemented. I'm just commenting here so that we can close both when the issue is implemented.

Status changed to closed

mentioned in merge request !94 (merged)

Status changed to closed

Closing since !94 (merged) got merged.

I hope this will be released soon, since the old changelog links are gone.

If you cannot wait until the stable, you can run a test release.