cmp: derive Clone for Ordering
cmp: add Ord+TotalOrd impls for Ordering itself
libcore: fix overflow/underflow in range_step
core: Remove all but one drop block in favor of `finally`
auto merge of #5769 : gifnksm/rust/range_step, r=bstrie

`uint::range_step` or `int::range_step` causes overflow or underflow as following.
code:
```rust
fn main() {
    for uint::range_step(3, 0, -2) |n| {
        println(fmt!("%u", n));
    }
}
```
output:
```
3
1
18446744073709551615
18446744073709551613
...
```
This commit fixes this behavior as follows.
```
3
1
```
Allow lint modes to be used on unused variables and dead assignments
Bump version to 0.7-pre
auto merge of #5805 : brson/rust/0.7-pre, r=brson
vim: syntax highlight for inner doc comment
auto merge of #5766 : thestinger/rust/cmp, r=brson

It was simpler to just give the variants a value instead of listing out all the cases for (*self, *other) in a match statement or writing spaghetti code. This makes the `cmp` method easier to use with FFI too, since you're a cast away from an idiomatic C comparator function. It would be fine implemented another way though.
auto merge of #5802 : nikomatsakis/rust/issue-4183-trait-substs, r=nikomatsakis

Cleanup substitutions and treatment of generics around traits in a number of ways

- In a TraitRef, use the self type consistently to refer to the Self type:
  - trait ref in `impl Trait<A,B,C> for S` has a self type of `S`.
  - trait ref in `A:Trait` has the self type `A`
  - trait ref associated with a trait decl has self type `Self`
  - trait ref associated with a supertype has self type `Self`
  - trait ref in an object type `@Trait` has no self type

- Rewrite `each_bound_traits_and_supertraits` to perform
  substitutions as it goes, and thus yield a series of trait refs
  that are always in the same 'namespace' as the type parameter
  bound given as input.  Before, we left this to the caller, but
  this doesn't work because the caller lacks adequare information
  to perform the type substitutions correctly.

- For provided methods, substitute the generics involved in the provided
  method correctly.

- Introduce TypeParameterDef, which tracks the bounds declared on a type
  parameter and brings them together with the def_id and (in the future)
  other information (maybe even the parameter's name!).

- Introduce Subst trait, which helps to cleanup a lot of the
  repetitive code involved with doing type substitution.

- Introduce Repr trait, which makes debug printouts far more convenient.

Fixes #4183.  Needed for #5656.

r? @catamorphism
auto merge of #5807 : klutzy/rust/vim-inner-doc, r=brson

Follow-up of #5760:
Add syntax highlight for `/*! doc */` or `//! doc`.
auto merge of #5789 : brson/rust/drop, r=graydon
auto merge of #5804 : alexcrichton/rust/issue-3266, r=graydon

This leaves the default lint modes at `warn`, but now the unused variable and dead assignment warnings are configurable on a per-item basis. As described in #3266, this just involved carrying around a couple ids to pass over to `span_lint`. I personally would prefer to keep the `_` prefix as well.

This closes #3266.
Revert map.each to something which takes two parameters
rather than a tuple.  The current setup iterates over
`BaseIter<(&'self K, &'self V)>` where 'self is a lifetime declared
*in the each method*.  You can't place such a type in
the impl declaration.  The compiler currently allows it,
but this will not be legal under #5656 and I'm pretty sure
it's not sound now.