Vim syntax file types and traits cleanup
Add examples for from_utf8_owned, from_char, from_chars, from_byte
auto merge of #15301 : jasonthompson/rust/docs/str2, r=alexcrichton
Improve rustdocs for Rc, add examples
doc: Clarify that an error is a compiler error

This was asked on HN, and it's easy to clarify.
auto merge of #15308 : brson/rust/intro, r=alexcrichton

This was asked on HN, and it's easy to clarify.
auto merge of #15251 : AlisdairO/rust/master, r=alexcrichton

I've seen quite a bit of confusion around regarding the use of Rc, so I thought I'd take a stab at adding some examples.
auto merge of #15292 : alxgnon/rust/vim_syntax_cleanup, r=cmr

- Fix a couple mistakes:
  - `Ordering` is an enum, not a trait.
  - `Container` is now named `Collection`.
  - Add missing `CheckedDiv`.
  - Remove obsolete `OwnedVector`.
- Reorganize some lines to match [prelude's arrangement](http://doc.rust-lang.org/std/prelude/#reexports), making mistakes easier to spot in the future.