Fix deprecated use of ~
rustc: Remove ~[T] from the language

The following features have been removed

* box [a, b, c]
* ~[a, b, c]
* box [a, ..N]
* ~[a, ..N]
* ~[T] (as a type)
* deprecated_owned_vector lint

All users of ~[T] should move to using Vec<T> instead.
auto merge of #14703 : alexcrichton/rust/no-more-owned-vectors, r=brson

The following features have been removed

* `box [a, b, c]`
* `~[a, b, c]`
* `box [a, ..N]`
* `~[a, ..N]`
* `~[T]` (as a type)
* deprecated_owned_vector lint

All users of ~[T] should move to using Vec<T> instead.
Improve docs and refactore std::os.
auto merge of #14713 : darnuria/rust/Improve_std_os_documentation_#2, r=alexcrichton

Improving documentation, consistency, removes evils empty lines etc...
auto merge of #14799 : mcreinhard/rust/tilde-fix, r=alexcrichton

Replaced `~Drawable` with `Box<Drawable>` in tutorial
std: Improve pipe() functionality

* os::pipe() now returns IoResult<os::Pipe>
* os::pipe() is now unsafe because it does not arrange for deallocation of file
  descriptors
* os::Pipe fields are renamed from input to reader and out to write.
* PipeStream::pair() has been added. This is a safe method to get a pair of
  pipes.
* Dealing with pipes in native process bindings have been improved to be more
  robust in the face of failure and intermittent errors. This converts a few
  fail!() situations to Err situations.

Closes #9458
cc #13538
Closes #14724
[breaking-change]