Now that `std::old_io` has been removed for quite some time the naming real
estate here has opened up to allow these modules to move back to their proper
names.
This commit is an implementation of [RFC 1044][rfc] which adds additional
surface area to the `std::fs` module. All new APIs are `#[unstable]` behind
assorted feature names for each one.
[rfc]: https://github.com/rust-lang/rfcs/pull/1044
The new APIs added are:
* `fs::canonicalize` - bindings to `realpath` on unix and
`GetFinalPathNameByHandle` on windows.
* `fs::symlink_metadata` - similar to `lstat` on unix
* `fs::FileType` and accessor methods as `is_{file,dir,symlink}`
* `fs::Metadata::file_type` - accessor for the raw file type
* `fs::DirEntry::metadata` - acquisition of metadata which is free on Windows
but requires a syscall on unix.
* `fs::DirEntry::file_type` - access the file type which may not require a
syscall on most platforms.
* `fs::DirEntry::file_name` - access just the file name without leading
components.
* `fs::PathExt::symlink_metadata` - convenience method for the top-level
function.
* `fs::PathExt::canonicalize` - convenience method for the top-level
function.
* `fs::PathExt::read_link` - convenience method for the top-level
function.
* `fs::PathExt::read_dir` - convenience method for the top-level
function.
* `std::os::raw` - type definitions for raw OS/C types available on all
platforms.
* `std::os::$platform` - new modules have been added for all currently supported
platforms (e.g. those more specific than just `unix`).
* `std::os::$platform::raw` - platform-specific type definitions. These modules
are populated with the bare essentials necessary for lowing I/O types into
their raw representations, and currently largely consist of the `stat`
definition for unix platforms.
This commit also deprecates `Metadata::{modified, accessed}` in favor of
inspecting the raw representations via the lowering methods of `Metadata`.
