libstd: Add some methods to `Vec<T>`.
test: Automatically remove all `~[T]` from tests.
test: Make manual changes to deal with the fallout from removal of
`~[T]` in test, libgetopts, compiletest, librustdoc, and libnum.
Remove outdated and unnecessary std::vec_ng::Vec imports.

(And fix some tests.)
Remove nearly all uses of `~[]` from libtest.

Deny further uses, with explicit allows on a few specific functions.
getopts: remove all uses of `~[]`.

And stop regressions with the lint.
Add #[deny(deprecated_owned_vector)] to several modules.
auto merge of #13056 : huonw/rust/devecing-tests, r=pnkfelix

test: Remove all `~[T]` from tests, libgetopts, compiletest, librustdoc, and libnum

And most from libtest, libflate, and adds `deny(deprecated_owned_vector)`s to the smaller modules with that have zero (or nearly zero) uses of `~[T]`.

Revival of #12837