This also adds a note about required memory usage and instructions for
building from Git.

Closes #7888

This will be needed to add `'static` bounds to `@`.

r? @nikomatsakis 

... in tree.

Fix #6929

I added these while tracking down heap corruption in Servo.

Fix warnings that only show up when compiling the tests for libstd, libextra and one in librusti. Only trivial changes.

This doesn't make sense under the new scheduler.

Closes #3816.

Without --quiet, git shows its own progress report of download. It's not really a progress bar, but it's a percentage and files incoming. This will help initial downloads of LLVM to not cause people to wonder why their configure script is hanging for hours.

r? @graydon

It's probably a good idea to at least *mention* them somewhere.

`pandoc` issues warnings.

```
pandoc: Duplicate link reference `[macros]' "source" (line 2151, column 1)
pandoc: Duplicate link reference `[tasks]' "source" (line 2150, column 1)
pandoc: Duplicate link reference `[wiki-start]' "source" (line 92, column 1)
```

This PR also removes unused link references.

Updated all users of HashMap, HashSet ::consume() to use
.consume_iter().

Since .consume_iter() takes the map or set by value, it needs awkward
extra code to in librusti's use of @mut HashMap, where the map value can
not be directly moved out.

Addresses issue #7719

Progress on #7824, closes #7825

Updated all users of HashMap, HashSet old .consume() to use .consume()
with a for loop.

Since .consume() takes the map or set by value, it needs awkward
extra code to in librusti's use of @mut HashMap, where the map value can
not be directly moved out.

Note that this is not actually *used* by default; it is a matter of
configuration still, because you might want to:

- Compile all .rs files with `rustc %` (where each can be built itself)

- Compile all .rs files with `rustc some-file.rs` (where you are editing
  part of a crate)

- Compile with a different tool, such as `make`. (In this case you might
  put a `~/.vim/after/compiler/rustc.vim` to match such cases, set
  makeprg and extend errorformat as appropriate. That should probably go
  in a different compiler mode, e.g. make-rustc.)

To try using it, `:compiler rustc`. Then, `:make` on a file you would
run `rustc` on will work its magic, invoking rustc. To automate this,
you could have something like `autocmd FileType rust compiler rustc` in
your Vim config.

r? anyone

The only bit that I'm a little concerned about is whether there's some way the assignments to `hi` could somehow still be necessary; but I think that could only be the case if it had been `&const` borrowed (or whatever the hypothetical syntax is for that), and that's not going on in this file.

This code looks like it was just wrong. r? @bblum

This will be needed to add `'static` bounds to `@`.

Most of these are "unneccesary allocation" in bitv, for ~[false, ..] instead
of [false, ..].

Closes #7860