Inline unit tests are so last decade

Aside from codebase-wide changes, nearly all of these tests have been
abandoned since at least 2010, and there is no effort to maintain this style
of testing. We've moved on to (correctly) separating out our tests from
our codebase.

The tests that are defined in `spec/` are run on every commit by our friends at Travis-CI, and there is some hope for resurrecting the practices in `test/modules/` (since module code is eval'ed, it's hard to test that kind of thing in a normal spec environment).