The issue fixed is that most Lisps don't like
*default-pathname-defaults* being a logical-pathname.
Added a test for logical-pathname functionality;
it all works on CCL, and works better on other Lisps after the fix,
but there are still logical-pathname issues on SBCL, CLISP and more.
Also, a package cleanup of our test suite.

Also, use coerce-pathname in asdf-ecl and deprecate merge-component-name-type.

Simplify test scripts.

perl -pi.bak -e 's|"../asdf"|\(compile-file-pathname "../asdf"\)|;' *.script

* made it easier to debug tests. export DEBUG_ASDF_TEST=t
* add ECL support to tests: passes all 18 scripts, but have to ignore compile warnings.
* lots of whitespace issues, including ones that made .gitignore not work!

Found that the current load recipe (load "../asdf") in the test
scripts was brittle, because the presence of asdf.fasl was obscured
if there was an "asdf/" directory in ..  Unfortunately, the result
of makeinfo --html asdf.texinfo created just such a directory!
fe[nl]ix kindly provided a pointer to compile-file-pathname that
solved the problem.

missing-dependency handling.