Create man pages for rust tools
Add new manpages to install script
Updated rustpkg man page to match 0.7
Constrain maximum lifetime of stack closures that capture variables to
be limited by the innermost repeating scope.

Fixes #7336.
iterator: add DoubleEndedIterator concept

This implements the trait for vector iterators, replacing the reverse
iterator types. The methods will stay, for implementing the future
reverse Iterable traits and convenience.

This can also be trivially implemented for circular buffers and other
variants of arrays like strings and `SmallIntMap`/`SmallIntSet`.

The `DoubleEndedIterator` trait will allow for implementing algorithms
like in-place reverse on generic mutable iterators.

The naming (`Range` vs. `Iterator`, `Bidirectional` vs. `DoubleEnded`)
can be bikeshedded in the future.
vec: rm inline(never) hack

just avoid giving an inline hint in the first place
dlist: A new implementation of an owned doubly-linked list

This is an owned sendable linked list which allows insertion and
deletion at both ends, with fast traversal through iteration, and fast
append/prepend.

It is indended to replace the previous managed DList with exposed list
nodes. It does not match it feature by feature, but DList could grow
more methods if needed.
dlist: Implement size_hint properly for all iterators
dlist: Introduce a struct Rawlink mimicing Option<T> for a raw pointer

Rawlink<T> holds a *mut T pointer and can convert itself to Option<&mut T>.
The null pointer is of course None.
dlist: Collect a common pattern into link_with_prev()
dlist: Put all tests into a tests module

The exception is the function check_links which needs access to struct
Node (which is not pub).
dlist: Expose ListInsertion trait with insert_before and peek_next

An iterator that allows mutating the list is very useful but needs care
to not be unsound. ListIteration exposes only insert_before (used for
insert_ordered) and peek_next so far.
extra: Add mod container with trait Deque
extra: Rename deque::Deque to ringbuf::RingBuf and impl trait Deque

Let RingBuf have a logical name for a concrete type, and Deque is
used for the Deque trait (implemented by RingBuf and dlist).
dlist: Implement trait Deque
dlist: Fix license header
dlist: Name the type DList for doubly-linked list
extra: Mention extra::container::Deque trait in doc for RingBuf and DList
auto merge of #7632 : gavinb/rust/7484_manpages, r=cmr

This patch updates the existing manpage and creates new pages for all of the rust command line tools. Closes #7484.
auto merge of #7455 : nikomatsakis/rust/issue-7336-constrain-closure-lifetimes, r=pnkfelix

Constrain maximum lifetime of stack closures that capture variables to be limited by the innermost repeating scope.

Fixes #7336.

r? whomever.