expose tokio_uds from the root crate

[casimir]

This is the start of the work to expose tokio_uds like tokio_tcp and tokio_udp. Just like in the std lib the export is only effective for unix systems.

There is to some points to discuss:

• I choose to follow the 3-letters convention with uds is that ok?
• Should there be more symbol exported (e.g. SendDgram, RecvDgram)? If so how to handle name conflict?
• I couldn't find how to handle the plateform-specific documentation.

[carllerche]

Thanks for doing this.

I would keep the names used in the sub crate (Unix*) to avoid confusion.

The only other question is if the types should be re-exported in tokio::net directly or a different module. std uses std::os::unix::net::UnixStream but I don't think I would mirror that. I would be fine with just using tokio::net except for the SendDgram RecvDgram conflict...

Here is my proposal, what are your thoughts?

// In `tokio::net`

#[cfg(unix)]
pub mod unix {
    //! Dox

    pub use tokio_uds::*;
}

pub use tokio_uds::{UnixListener, UnixStream};

Eventually, we could add a udp module and move UDP's RecvDgram and SendDgram types into there to avoid polluting tokio::net with types that will rarely be used directly.

[casimir]

I like the pattern you propose: 1 module for 1 crate and only the most used symbols in tokio::net for convenience. I updated the PR in consequence (sorry for the force-push I mixed up my git commands). Let me now if something is still missing.

After this PR I can take care of the tcp and udp module if you're still up to this.

[carllerche]

Looks good to me 👍

@seanmonstar, you good w/ this layout?

Re: TCP / UDP, I would definitely take a PR. You will just have to make sure to not introduce breaking changes. Instead, hide types from docs & flag the exports as deprecated.

[casimir]

Just updated the commit to fix conflicts with master.