Automated conversion using the untry tool [1] and the following command:
```
$ find -name '*.rs' -type f | xargs untry
```
at the root of the Rust repo.
[1]: https://github.com/japaric/untry
This is a new suite of tests that verifies that the compiler
builds specific revisions of select crates from crates.io.
It does not run by default. It is intended that buildbot
runs these tests against all PRs, and gate on them.
Add a script to get run which verifies that `href` links in documents are
correct. We're always getting a steady stream of "fix a broken link" PRs and
issue reports, and we should probably just nip them all in the bud.
