Make sure we (re)initialize-asdf at some early point: things may have changed after image-dump.

Notably, pass around the location of the xcvb-program we create in the cache.

* Use define-command to define and register a command
* Introduce the notion of workspace to store intermediate and target files.
* Update Makefiles for new intended output paths

Fix a few glaring recent bugs.

* extract fasl type from target:
 at least lispworks depends on pathname type and its fasl type varies!
* rucksack not available on clisp (and needed fixes; see our xcvb repo of it)
* accept compile-file failure semantics of clisp
* suppress duplicate entries for a directory in the source-registry:
 The first one wins, with its recurse and exclude flags.
* fix hello and test/runme
* fix various option parsing mistakes

	settings known to xcvb or the individual value of a single one.
Change the default object-directory location to be
	$HOME/.cache/xcvb/common-lisp/<lisp-implementation-version>/
Added format! in driver.lisp to help with debugging and forcing output.
Debugged CMUCL support in driver.
Fixed implementation-identifier support in extract-target-properties.
Allowed Makefile in example-1 to parameterize on lisp implementation.
Refactored how option-specs are specified for command line options.
Removed dead code paths from simple-build backend that dealt with
	"xcvb.mk" and the makefile output file.
Muffled warnings when loading asdf.
Added target-asdf-version setting which you can query with show-settings.
Started DONE.rest

transient threads created by posix_spawn. Sigh.

My, that what much more painful than it ought to be.

TODO for ECL: distinguish linkable object files from loadable shared objects.

* fix various bugs left over from .507.
* back out generation of Lisp files in object tree
 until we can provide build processes with a mapping from name to pathname.
* pass self-test.

* after profiling, too much time was spent in checking directories to make.
 Using a hash-table of implicitly (or explicitly) made directories
 as well as a list of explicitly made directories.
* use asdf-dependency-grovel::normalized-component-name
 for names of components included.
* Idea: give a number to each grain, then use FMIM for mergeable sets of
 grains (if lots of reuse - use hash-consing of sets of grains?).

Some documentation update.
Tweak hello Makefile for ASDF 2.
re-Hush warning from registry.
Add require-asdf.

Easy functionality: version, ssr and a2x work.

* The Makefile has a pre-release-test target, so no need to commit
 "yet another attempt at auto-validated release" anymore --
 I will test whether the code I have passes muster before committing.
* error out early if XCVB_OBJECT_DIRECTORY wasn't configured.
* Fixes to the regressions in the non-enforcing backend that had been
 made to implicitly rely on a previous run of the enforcing backend.
* Factoring out common option handling.
* Removing cruft from previous over-design of the computation class.
* Many thanks to Attila Lendvai for testing.

change SBCL_HOME unsetting to be less uniform but more portable.
Fix posix-wait in CLISP as in the recent POIU fix.
My, we need a regression test suite!

* Introduce the world-grain abstraction as a step towards a farmer.
* A few important cleanups and refactorings.
* better hush the build

+ shuffling code outside of main.lisp
+ a bit of farming

* will now correctly load specified setup
* will automatically configure ASDF to find POIU

Also
* will correctly configure *xcvb-lisp-directory* with the XCVB installation path.
* some docs about XCVB vs ASDF-BINARY-LOCATIONS and ASDF-SYSTEM-CONNECTIONS
* initial stubs for xcvb-master.

Complete the non-enforcing makefile backend.
Refactor a bit the asdf backend along the way.
Debug portablish-pathname, main.

Had to do a few things by hand to compile xcvb itself with poiu:
   mkdir obj-ne ; ln -s ../../poiu/poiu.asd obj-ne/ ;
   xcvb nm --build xcvb --parallel && make -f xcvb-ne.mk

Nothing functional yet, but checkpointing my work.
More documentation update.