A typo in the Makefile was causing these to not run. Happily, a lot of these
tests pass, so un-xfailed.

Un-xfail spawn-non-nil-fn

Add quick_sort3 function based on 'QuicksortIsOptimal.pdf' (see comments in file). Cleanup the quick_sort function a little, as well. Add test file.

Just removing some unnecessary imports.

This only happened for single-length import paths, because the import
was being looked up in its own scope.

The error message for (for example) "import vec;" without "use std;"
was "cyclic import", which was misleading because there were no
cycles. I changed it to "cyclic import or nonexistent module",
which doesn't break existing tests.

This was a rustboot-specific test which is covered by other tests in rustc.

Changed a few error patterns to match rustc's errors where it seemed
reasonable.

and update it to reflect the new friendly error message

If a type still contains free type variables after typechecking (for
example, as with "auto foo = []", the result was an assertion failure
in typeck. Made it a human-readable error message instead.

Previously, if you wrote
let @vec[int] foo = @[];

that would be a type error. That didn't seem right, so I changed
pushdown to unify the inner type in an unop application with the
argument type of the operator type.

The optimization passes were hiding some codegen errors so now we run the
verifier both before and after optimization.

Workaround for issue #375

This involved a small fix to the unicode-escape character lexing and
to the pretty-printer.

Apparently my version of texinfo doesn't require curly braces to be escaped, but the buildbot's version does...