FeatureRequest: Add support for continued download.

[songww]

Thanks for your project.

When a file fails to download, it is always necessary to start the download from the beginning.
When the network is not good, it is too difficult to complete the download at a time.

Sorry, my english is poor.

[BreezeWhite]

We are currently not having enough human resources to develop new features, but checkpoints can be manually downloaded separately through the release.