`Reply` trait is public but not meaningfully usable

[FeldrinH]

Currently the Reply trait is public, but it cannot be used in any meaningful way, because its only method requires an instance of ReplySender which is private and only has private implementors.

What is the purpose of having Reply in the public API? Looking at the code it seems to be an internal implementation trait that should not be exposed to users.

[FeldrinH]

Same question about ReplyDirectory::new and ReplyDirectoryPlus::new.

[cberner]

A lot of the code in fuser is from a previous maintainer. The Reply trait included. Feel free to submit PRs that clean up parts of the public API, which obviously do not make sense