Pushed ASDF 3.1.7.8: fixes for CLISP, etc.

[Faré]

Sam Steingold (sds) probed me on some old bugs, which led me to waste
a day debugging issues on and with CLISP.

First I reproduced CLISP bug 677, figured out what CLISP was doing
wrong (incorrect merging of logical pathnames in compile-file), and
implemented a workaround (physicalize everything I can, trust
compile-file's return value over my :output-file argument):
https://sourceforge.net/p/clisp/bugs/677/

Then, I found a cleaner fix to the issue with DIRECTORY wanting "*"
rather than "*.*" as the match-all pattern on CLISP and GCL.

I also dug out the information in the old README.md that Robert
stripped. I moved anything that may have been redundant with
doc/index.html, move there what was complementary, and put back in
README.md (after some editing) things that were not covered by either
the home page or the manual: the documentation on how to navigate our
source code, build and test ASDF, etc.

Robert, please tell me if that's OK, since you were the one who
deleted that information arguing of unmaintainable redundancy with web
page and manual.

I also slightly tweaked said web page and manual.

Also, I see you disabled make doc in the Makefile. I presume it should
be restored.

Finally, I renamed make.bat to make-asdf.bat so that on Windows there
is no risk of typing "make" and run make.bat in the current directory
while believing one had run make.exe from the %PATH%. This may or may
not help Robert make his tests pass on Windows.

—♯ƒ • François-René ÐVB Rideau •Reflection&Cybernethics• http://fare.tunes.org
...so this guy walks into a bar.
"The usual, Mr. Descartes?" the barman asked.
"I think not," Rene replied, and promptly disappeared.