std::iter: Introduce .by_ref() adaptor

Creates a wrapper around a mutable reference to the iterator.

This is useful to allow applying iterator adaptors while still
retaining ownership of the original iterator value.

Example::

   let mut xs = range(0, 10);
   // sum the first five values
   let partial_sum = xs.by_ref().take(5).fold(0, |a, b| a + b);
   assert!(partial_sum == 10);
   // xs.next() is now `5`
   assert!(xs.next() == Some(5));
std::rt::uv::net: Handle `read_start` error

cc #9605
std::rt: Add NotConnected to IoErrorKind
rt::io::net::tcp: Fix eof_twice tests on Win32

cc #8811
extra: implement Encodable/Decodable for Uuid
rustdoc: Use privacy visibility for pruning

This commit ends rustdoc's approximation of privacy and instead uses the result
of the various compiler passes instead.

Closes #9827
rustdoc: Don't abort if there's nothing to document

Instead there's no index.html file emitted because there wasn't anything to
document.

Closes #9828
Require module documentation with missing_doc

Closes #9824
Build a few extra features into format! parsing

* Allow named parameters to specify width/precision
* Intepret the format string '0$' as "width is the 0th argument" instead of
  thinking the lone '0' was the sign-aware-zero-padding flag. To get both you'd
  need to put '00$' which makes more sense if you want both to happen.

Closes #9669
Allow stage0 warnings
auto merge of #9634 : blake2-ppc/rust/by-ref-iter, r=thestinger

std::iter: Introduce .by_ref() adaptor

Creates a wrapper around a mutable reference to the iterator.

This is useful to allow applying iterator adaptors while still
retaining ownership of the original iterator value.

Example::

    let mut xs = range(0, 10);
    // sum the first five values
    let partial_sum = xs.by_ref().take(5).fold(0, |a, b| a + b);
    assert!(partial_sum == 10);
    // xs.next() is now `5`
    assert!(xs.next() == Some(5));

---

This adaptor requires the user to have good understanding of
iterators or what a particular adaptor does. There could be some
pitfalls here with the iterator protocol, it's mostly the same issues
as other places regarding what happens after the iterator
returns None for the first time.

There could also be other ways to achieve the same thing, for
example Implementing iterator on `&mut T` itself:
`impl <T: Iterator<..>> Iterator for &mut T`  but that would only
lead to confusion I think.
auto merge of #9833 : alexcrichton/rust/fixes, r=brson

Commits have all the fun details
uuid: serialize test and documentations
auto merge of #9721 : klutzy/rust/uv-net-read-fix, r=alexcrichton

See #9605 for detailed information.

This also fixes two tests of #8811.
remove the rusti command

Closes #9818
Closes #9567
Closes #8924
Closes #8910
Closes #8392
Closes #7692
Closes #7499
Closes #7220
drop the linenoise library

Closes #5038
Added comments to public functions in num.rs.

Copied existing comments from other files, and added comments to
functions that did not have existing comments available.
auto merge of #9585 : vky/rust/num-docs, r=alexcrichton

Copied existing comments from other files, and added comments to functions that did not have existing comments available. 

cc #7511
Removed the -Z once_fns compiler flag and added the new feature directive of the same name to replace it.
Changed the frame_address intrinsic to no longer be a once fn.
This removes the dependency on once_fns from std.
auto merge of #9846 : cmr/rust/serialize_uuid, r=alexcrichton