Fixes: lp#1042691 (thanks, stassats)

This fix is from Mr. Kiyoshi Mizumaru.  It adds an "S" to the
lisp-version-string in the ACL SMP case.

based on code by MKCL's Jean-Claude Beaudoin.

Tested: CCL, ECL, SBCL.

* Refactor load-system to use *load-system-operation*,
and change require-system and module-provide-asdf to use that.
* Remove broken-fasl-support: first, cormanlisp is supposed to have fixed it;
 second, cormanlisp is dead;
 third, one can now (setf *load-system-operation* 'load-source-op) instead.
* Reindent default-source-registry
* Fix a test in light of some previous package frobbing.

modulo remarks sent on the mailing-list.

This allows for consistency check of .fasl output before the file can possibly be seen
by other builds (i.e. no race condition).

for which we do extra magic filtering. Should make Erik Pearson happy re lp#1000842.

Thanks to Erik Pearson for prompt bug report.

following discussion with Nikodemus on asdf-devel.
Also, improve the way we test for upgrade.
Disable upgrade test on cmucl from asdf 2.00*.
Restore -i.bak flag in bump-version: it's actually needed.

Update documentation somewhat.

to make Erik Pearson happy.

Fix a misparenthetization in 2.20.12 that disabled windows shortcut.

by using unintern rather than fmakunbound for redefined generic functions.

This matters if you e.g. open asdf.lisp in LispWorks before you load it,
in which case it will automatically create an ASDF package
with a default use list that pulls in symbols from LispWorks's own defsystem.
Also, export strcat.

Add a hook to autodetect file encoding.
Don't use :unspecific on ecl, it breaks asdf-pathname-test.script
Disable warnings testing when compiling asdf with SCL. Bug in SCL?

This ensures backwards compatibility with 2.20 and earlier,
for now, until the dust settles on asdf encodings.
Update documentation about encodings.
Export more utilities. Document some of them.
Remove ununspecific. Accept :unspecific on more implementations.

Make logical pathname test work on disjoint files, for now.
Fix test-upgrade wrt recent package tweak in testing.

Avoid error from missing system's source-file when upgrading from ASDF 1.

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.