Tests: SBCL passes test-lisp and test-upgrade
Also:
* big refactoring of test infrastructure
* contrib/debug.lisp and (asdf/driver:asdf-debug) for debugging.
* remove aif and it, use the cleaner if-bind.
* backtrace support, with improvements from trivial-backtrace.
* integration of asdf-condition-control (originally from xcvb-driver)
* simplify the upgrade heuristic: always tries to upgrade once.
  The previous heuristic was too complex with too many failure cases.
  You are thus assumed to want a given version asdf
  if and only if it is in your source-registry.

Major change for RMCL: location strings are now POSIX namestrings.
Major change for logical pathnames: they are now preserved by source-registry;
the price is that only logical pathnames for which merging the name and type
commutes with truename will be found by directory-files and subdirectories.
Minor change for GCL: dropped kluges for 2.6, which never was working.
Simplifications in internals of (implementation-identifier).
Removed *system-cache* and get-uid, which never were working right
(bad attempts at allowing common-lisp-controller compatibility,
but it only ever was but a giant gaping security hole in the waiting).
Simplified resolve-relative-location-component
(ugly because it was written before MERGE-PATHNAMES*).
Updated documentation about the file location DSL.

Use probe-file for probe-file* in LispWorks.

Make ABCL's jar translation happier with
the recent compile-file-pathname* change for Stelian by redoing cfp myself.

Make truenamize work when the merged pathname is relative.
Makes it happier when e.g. the *default-pathname-defaults* is #p"",
which is the case notably on CCL.

Try and fail to support GCL 2.6 and have 2.7 fail less;
too many bugs, in CONDITIONs, PATHNAMEs, and more,
plus compiler bug that breaks coerce-pathname.

Cleanup the search-for-system-definition protocol.
Define upgrade-asdf function.
Cache the source-registry scan in a hash-table.

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

ATTENTION: incompatible change to component-name-to-pathname-components
Also, have compile-file* heed a :output-file parameter.

Also, allow for upgradability from old ASDF versions that don't have system-source-file.

Fix link in webpage (lp#614806).
Include SCL and ABCL in my testing routine.

Move test results in tmp/ directory.

* Fix initialize-output-translations to actually use the environment,
 map output destinations to themselves, and
 actually take a parameter as documented.
* Document same parameter for initialize-source-registry, which did take it.
* Tweak symbols between unintern and fmakunbound
 to make upgrade better on both current SBCL and ECL.
* Tweak run-tests to allow for parametrizable binaries,
 to redirect output to tmp/fasls, to output Lisp command being executed,

Add janderson's pathname test script to our test suite.