Require `make` is run before `make install`

I can't quite remember why this ifdef is present to silently run `make` as a
normal user, and it doesn't seem to work if `make install` is run while as root,
so I'm just removing it and requiring that `make` is run before `make install`
unconditionally.

Closes #708
Allow reexporting of features between packages

As pointed in #633, it's currently not possible for a package to reexport the
feature of another package due to the limitations of how features are defined.

This commit adds support for this ability by allowing features of the form
`foo/bar` in the `features` section of the manifest. This form indicates that
the dependency `foo` should have its `bar` feature enabled. Additionally, it is
not required that `foo` is an optional dependency.

This does not allow features of the form `foo/bar` in a `[dependencies]`
features section as dependencies shouldn't be enabling features for other
dependencies.

Closes #633
Closes #674
Pass features to native build commands

Closes #97
Closes #601 (this is an equivalent solution for that problem)
Update to rust master to remove libdebug
auto merge of #719 : alexcrichton/cargo/update-docopt, r=alexcrichton
auto merge of #712 : alexcrichton/cargo/issue-633, r=brson

As pointed in #633, it's currently not possible for a package to reexport the
feature of another package due to the limitations of how features are defined.

This commit adds support for this ability by allowing features of the form
`foo/bar` in the `features` section of the manifest. This form indicates that
the dependency `foo` should have its `bar` feature enabled. Additionally, it is
not required that `foo` is an optional dependency.

This does not allow features of the form `foo/bar` in a `[dependencies]`
features section as dependencies shouldn't be enabling features for other
dependencies.

At the same time, this passes through features to build commands to solve a few more issues.

Closes #97
Closes #601 (this is an equivalent solution for that problem)
Closes #633
Closes #674
Remove dependence on various plugins

It's looking more likely like plugins will not make it into the stable channel
of Rust, so this commits removes Cargo's personal dependence on the two
plugin-based pieces of functionality it was using:

1. Uses of the `regex!` macro now go through `Regex::new`.
2. Uses of the `docopt!` macro now go through `deriving(Decodable)` instead.
auto merge of #711 : alexcrichton/cargo/issue-708, r=brson

I can't quite remember why this ifdef is present to silently run `make` as a
normal user, and it doesn't seem to work if `make install` is run while as root,
so I'm just removing it and requiring that `make` is run before `make install`
unconditionally.

Closes #708
auto merge of #720 : alexcrichton/cargo/no-more-plugins, r=brson

It's looking more likely like plugins will not make it into the stable channel
of Rust, so this commits removes Cargo's personal dependence on the two
plugin-based pieces of functionality it was using:

1. Uses of the `regex!` macro now go through `Regex::new`.
2. Uses of the `docopt!` macro now go through `deriving(Decodable)` instead.
Update docs url
auto merge of #721 : EduardoBautista/cargo/update-docs-url, r=alexcrichton
document rpath option in manifest
use rpath defaults
auto merge of #722 : blaenk/cargo/rpath-docs, r=alexcrichton

The `rpath` option was added (awesome!) but not documented.
Replace usage of `get_ref`
Add general doccomments
Merge commit 'jdeseno/remove-deprecated' into update
Merge remote-tracking branch 'tomaka/add-docs' into update
Update dependencies to unbreak the build
auto merge of #732 : alexcrichton/cargo/update, r=alexcrichton

Also merge some other PRs while I'm at it