2.10.1 release with improved hash cache

(In fact, this release followed 2.10.0 by only a few days, and thus has been available since 9th of September. Due to lack of time it wasn't formally announced earlier. Apologies.)

2.10.1 revised the metalink hash cache again, after it was found that some filesystems do not guarantee stable inode numbers. To avoid expensive regeneration of hashes, previously existing hash files are automatically migrated. As a new feature, the metalink-hasher can now easily be run in parallel on large file trees, since it uses per-directory locking to make sure that two jobs won't work on the same files.

For details, please read the 2.10.1 release notes.