This restores third-party (ab)users of the Chibi macro system such
as in https://gist.github.com/baguette/2632464, while allowing us
to break those uses in more interesting ways.
It also keeps the core slightly smaller (both in C and Scheme)
and speeds up the macro expansion process.
By convention, a library meant for testing exports "run-tests".
Also by convention, assume the test for (foo bar) is (foo bar-test),
keeping the test in the same directory and avoiding confusion since
(chibi test) is not a test for (chibi).
- Avoids the hack of "load"ing test, with resulting namespace complications.
- Allows keeping tests together with the libraries.
- Allows setting up test hooks before running.
- Allows implicit inference of test locations when using above conventions.
