pull extra::{serialize, ebml} into a separate libserialize crate

- `extra::json` didn't make the cut, because of `extra::json` required
   dep on `extra::TreeMap`. If/when `extra::TreeMap` moves out of `extra`,
   then `extra::json` could move into `serialize`
- `libextra`, `libsyntax` and `librustc` depend on the newly created
  `libserialize`
- The extensions to various `extra` types like `DList`, `RingBuf`, `TreeMap`
  and `TreeSet` for `Encodable`/`Decodable` were moved into the respective
  modules in `extra`
- There is some trickery, evident in `src/libextra/lib.rs` where a stub
  of `extra::serialize` is set up (in `src/libextra/serialize.rs`) for
  use in the stage0 build, where the snapshot rustc is still making
  deriving for `Encodable` and `Decodable` point at extra. Big props to
  @huonw for help working out the re-export solution for this

extra: inline extra::serialize stub

fix stuff clobbered in rebase + don't reexport serialize::serialize

no more globs in libserialize

syntax: fix import of libserialize traits

librustc: fix bad imports in encoder/decoder

add serialize dep to librustdoc

fix failing run-pass tests w/ serialize dep

adjust uuid dep

more rebase de-clobbering for libserialize

fixing tests, pushing libextra dep into cfg(test)

fix doc code in extra::json

adjust index.md links to serialize and uuid library

1 files changed, 3 insertions, 2 deletions

diff --git a/src/doc/index.md b/src/doc/index.md
index 5aa92c9fec4..54b8b484693 100644
--- a/src/doc/index.md
+++ b/src/doc/index.md
@@ -41,9 +41,10 @@ li {list-style-type: none; }
 * [The `flate` compression library](flate/index.html)
 * [The `glob` file path matching library](glob/index.html)
 * [The `semver` version collation library](semver/index.html)
-* [The `term` terminal-handling library](term/index.html)
-* [The UUID library](uuid/index.html)
+* [The `serialize` value encoding/decoding library](serialize/index.html)
 * [The `sync` library for concurrency-enabled mechanisms and primitives](sync/index.html)
+* [The `term` terminal-handling library](term/index.html)
+* [The `uuid` 128-bit universally unique identifier library](uuid/index.html)
 
 # Tooling