This commit is an implementation of [RFC 807][rfc] which adds a `std::net`
module for basic neworking based on top of `std::io`. This module serves as a
replacement for the `std::old_io::net` module and networking primitives in
`old_io`.
[rfc]: fillmein
The major focus of this redesign is to cut back on the level of abstraction to
the point that each of the networking types is just a bare socket. To this end
functionality such as timeouts and cloning has been removed (although cloning
can be done through `duplicate`, it may just yield an error).
With this `net` module comes a new implementation of `SocketAddr` and `IpAddr`.
This work is entirely based on #20785 and the only changes were to alter the
in-memory representation to match the `libc`-expected variants and to move from
public fields to accessors.
This commit is an implementation of [RFC 739][rfc] which adds a new `std::fs`
module to the standard library. This module provides much of the same
functionality as `std::old_io::fs` but it has many tweaked APIs as well as uses
the new `std::path` module.
[rfc]: https://github.com/rust-lang/rfcs/pull/739
