Print a message when a command receives a signal

Receiving a signal is normally indicative of violent termination, so the
subcommand can't be relied upon to have printed some status information. As a
result, signals now have some extra errors printed to stderr when they fail.

Closes #261. The actual signal is still a bug, but it's an upstream rust bug.
Inherit stdin when using `cargo run`

Previously a pipe was made which could mess with stdin like in #267.

Closes #267
Add a cargo-doc command
Correctly discover exe suffix through rustc

There was a bug when this was written in rustc that prevented this, but it has
since been fixed.
auto merge of #276 : alexcrichton/cargo/fix-exe, r=carllerche

There was a bug when this was written in rustc that prevented this, but it has
since been fixed.
auto merge of #265 : alexcrichton/cargo/issue-261, r=wycats

Receiving a signal is normally indicative of violent termination, so the
subcommand can't be relied upon to have printed some status information. As a
result, signals now have some extra errors printed to stderr when they fail.

Closes #261. The actual signal is still a bug, but it's an upstream rust bug.
auto merge of #254 : alexcrichton/cargo/cargo-doc, r=wycats

This is blocked until https://github.com/rust-lang/rust/pull/15939 lands, but in the meantime I figured I could get some eyes on this to make sure I'm sane.

Closes #130
auto merge of #268 : alexcrichton/cargo/issue-267, r=wycats

Previously a pipe was made which could mess with stdin like in #267.

Closes #267
Move from hammer to docopt for option parsing

The hammer library currently has some shortcomings such as the inability to
document individual options. Additionally our handling with hammer of extra
arguments is dodgy at best currently.

This commit moves the repository to BurntSushi's docopt.rs library which seems
to more feature-complete at this time. Additionally, docopt has the great
benefit of a "document once, use everywhere" documentation strategy.

This migration solves two primary issues:

* Comprehensive and useful CLI documentation
* Gracefully handling flavorful combinations of arguments in odd combinations

Closes #218
auto merge of #266 : alexcrichton/cargo/docopt, r=wycats

The hammer library currently has some shortcomings such as the inability to
document individual options. Additionally our handling with hammer of extra
arguments is dodgy at best currently.

This commit moves the repository to BurntSushi's docopt.rs library which seems
to more feature-complete at this time. Additionally, docopt has the great
benefit of a "document once, use everywhere" documentation strategy.

This migration solves two primary issues:

* Comprehensive and useful CLI documentation
* Gracefully handling flavorful combinations of arguments in odd combinations
Deny all warnings when building cargo

This helps keep the build a little cleaner and any breakage that happens due to
rust changing will likely be mitigated by nightlies.
auto merge of #281 : alexcrichton/cargo/no-more-warnings, r=wycats

This helps keep the build a little cleaner and any breakage that happens due to
rust changing will likely be mitigated by nightlies.
Add a configure script

This configure script is similar to rust's in that it doesn't require anything
like autotools, it's just a meta-script to "generate" a makefile and perform
run-of-the-mill validation/discovery before the Makefile is run.

The main purpose of this rewrite is to support multi-target and targeted builds.
This will allow us to produce 32-bit snapshots for platforms as well as easily
providing `./configure --target $foo` for initialization.

cc #274