vim: Update syntax file for Prelude changes.

Lots of Vector -> Slice renames.
Optimized IR generation for UTF-8 and UTF-16 encoding

- Both can now be inlined and constant folded away
- Both can no longer cause failure
- Both now return an `Option` instead

Removed debug `assert!()`s over the valid ranges of a `char`
- It affected optimizations due to unwinding
- Char handling is now sound enought that they became uneccessary
Add `use a::b::{c, mod};` to the manual
collections: deprecate BTree.

This is very half-baked at the moment and very inefficient, e.g.
inappropriate use of by-value `self` (and thus being forced into an
overuse of `clone`). People get the wrong impression about Rust when
using it, e.g. that Rust cannot express what other languages can because
the implementation is inefficient.
Add new keywords (particularly `where` & `virtual`) to editor modes.
librustc: Forbid external crates, imports, and/or items from being
declared with the same name in the same scope.

This breaks several common patterns. First are unused imports:

    use foo::bar;
    use baz::bar;

Change this code to the following:

    use baz::bar;

Second, this patch breaks globs that import names that are shadowed by
subsequent imports. For example:

    use foo::*; // including `bar`
    use baz::bar;

Change this code to remove the glob:

    use foo::{boo, quux};
    use baz::bar;

Or qualify all uses of `bar`:

    use foo::{boo, quux};
    use baz;

    ... baz::bar ...

Finally, this patch breaks code that, at top level, explicitly imports
`std` and doesn't disable the prelude.

    extern crate std;

Because the prelude imports `std` implicitly, there is no need to
explicitly import it; just remove such directives.

The old behavior can be opted into via the `import_shadowing` feature
gate. Use of this feature gate is discouraged.

This implements RFC #116.

Closes #16464.

[breaking-change]
auto merge of #16482 : pcwalton/rust/resolve-shadowing, r=brson

declared with the same name in the same scope.

This breaks several common patterns. First are unused imports:

    use foo::bar;
    use baz::bar;

Change this code to the following:

    use baz::bar;

Second, this patch breaks globs that import names that are shadowed by
subsequent imports. For example:

    use foo::*; // including `bar`
    use baz::bar;

Change this code to remove the glob:

    use foo::{boo, quux};
    use baz::bar;

Or qualify all uses of `bar`:

    use foo::{boo, quux};
    use baz;

    ... baz::bar ...

Finally, this patch breaks code that, at top level, explicitly imports
`std` and doesn't disable the prelude.

    extern crate std;

Because the prelude imports `std` implicitly, there is no need to
explicitly import it; just remove such directives.

The old behavior can be opted into via the `import_shadowing` feature
gate. Use of this feature gate is discouraged.

This implements RFC #116.

Closes #16464.

[breaking-change]

r? @brson
Fix an error in a code sample in bitv.rs
auto merge of #16498 : Kimundi/rust/inline-utf-encoding, r=alexcrichton

The first commit improves code generation through a few changes:
- The `#[inline]` attributes allow llvm to constant fold the encoding step away in certain situations. For example, code like this changes from a call to `encode_utf8` in a inner loop to the pushing of a byte constant:

 ```rust
let mut s = String::new();
for _ in range(0u, 21) {
        s.push_char('a');
}
```
- Both methods changed their semantic from causing run time failure if the target buffer is not large enough to returning `None` instead. This makes llvm no longer emit code for causing failure for these methods.
- A few debug `assert!()` calls got removed because they affected code generation due to unwinding, and where basically unnecessary with today's sound handling of `char` as a Unicode scalar value.

~~The second commit is optional. It changes the methods from regular indexing with the `dst[i]` syntax to unsafe indexing with `dst.unsafe_mut_ref(i)`. This does not change code generation directly - in both cases llvm is smart enough to see that there can never be an out-of-bounds access. But it makes it emit a `nounwind` attribute for the function. 
However, I'm not sure whether that is a real improvement, so if there is any objection to this I'll remove the commit.~~

This changes how the methods behave on a too small buffer, so this is a 

[breaking-change]
auto merge of #16535 : michaelsproul/rust/vim-traits, r=pcwalton

The vim syntax highlighting file had become out of sync with the real prelude.

Lots of Vector -> Slice renames have happened recently.
librustc: Allow trait bounds on structures and enumerations, and check
them during kind checking.

This implements RFC #11.

Closes #15759.
auto merge of #16432 : pcwalton/rust/kindck-traits, r=nikomatsakis

them during kind checking.

This implements RFC #11.

Closes #15759.

r? @nikomatsakis
auto merge of #16537 : jakub-/rust/use-mod-manual, r=alexcrichton
auto merge of #16543 : huonw/rust/deprecated-btree, r=alexcrichton

This is very half-baked at the moment and very inefficient, e.g.
inappropriate use of by-value `self` (and thus being forced into an
overuse of `clone`). People get the wrong impression about Rust when
using it, e.g. that Rust cannot express what other languages can because
the implementation is inefficient: https://news.ycombinator.com/item?id=8187831 .
auto merge of #16547 : huonw/rust/new-kw, r=pcwalton
auto merge of #16550 : kaseyc/rust/fix_documentation_error, r=alexcrichton
Introduce lifetime bounds on iterators and other types as needed.
Rewrite Vec iterators to use a transmute and named lifetime so as to meet lifetime requirements
Introduce annotations on object types as required.
Annotate objects in the macro system. Unlike most objects, these ones actually close over references sometimes.