mk: Fix formatting of docs.mk
Added in Clone/TotalEq/TotalOrd/ToStr traits to all parts of btree.
Equals is now compact and uses vec's equals method.  Cmp compares
all elements on branches and leaves (Nodes).
doc: Update style of index, organization and trim out some excess.
Add Pointer tutorial, rename borrowed pointer tutorial.
doc: Fix tests in pointer guide
Remove trailing whitespace
Make CFG_LIBDIR configurable. Fixes #5223
auto merge of #11263 : niftynif/rust/btree, r=catamorphism

Apologies for junking up the feed with all of these separate pull requests.  I'm still getting the hang of git and will hopefully be doing less of this nonsense soon.  I opened up another PR and closed the one from earlier today because the first PR was coming from the wrong branch of my repo.
Anyway, this contains a fleshed-out implementation of TotalEq/TotalOrd/Clone/ToStr for the whole B-tree structure and relevant tests, integrating suggestions and comments from several community members.
r? @catamorphism
auto merge of #11045 : jhasse/rust/patch-libdir, r=alexcrichton

See https://github.com/mozilla/rust/issues/5223#issuecomment-30455086
auto merge of #11364 : brson/rust/docs, r=alexcrichton

This reorganizes the documentation index to be more focused on the in-tree docs, and to clean up the style, and it also adds @steveklabnik's pointer guide.
Renamed Option::map_default and mutate_default to map_or and mutate_or_set
Remove unnecessary substitution of type params when generating
vtable methods before translating the ref to the method itself.
libextra: Introduce typed arenas.

A typed arena is a type of arena that can only allocate objects of one
type. It is 3x faster than the existing arena and 13x faster than malloc
on Mac.
librustc: Move block contexts into per-function arenas, and
stack-allocate function contexts.
doc: Syntax highlight the cheatsheet
doc: Fix table format in cheatsheet
doc: Title guides consistently
mk: Start testing the cheatsheet
doc: Highlight the testing guide correctly
mk: Fix the naming of the windows installer harder

CFG_VERSION includes a bunch of VCS info in it that is not a valid
filename. CFG_RELEASE is just the version number.