Abandoning the idea of integrated config--inigrep should appear as "just
another config infra".

A little improved module finder now

 *  ignores non-directories (incl. non-existent),
 *  sends path to debug before visit,
 *  and is safe against paths with spaces,

but as a side effect

 *  invokes find per (valid directory) path.

If for certaiun group a mode is not specified, fall back to
a value inhertited from environment, or eventually to 644.

No need to use debugging in this stable feature

More understandable comand name.

The method is strange and has unexpected dependencies.  Putting the
responsibility to prepare tfkit to Makefile author's hands seems
cleaner--they need to set TF_DIR properly so it's sort of intuitive;
also it allows them to choose way how to deploy tfkit itself (sub-repo,
submodule, or hard copy).

Remove most of half-done things.

Try to make ffoo as small as possible.

Some things may return soon, others not.

... against conflict when -v is used and the name is exactly this.

Remove this questionable feature now and save variable name conflicts
later.

so that tfkit can now be tracked in separate repo.  (In future we might
add it as submodule)

Folow-up to 37b5db9 and 9c94a46.

Source the setup/cleanup code so that it can be used to prepare
environment.

Disadvantage is that the files will need to be in Bash (ie. effect of
commit 4eb772d is negated), but that should not be problem as the use
of subtest.sh already implies that Bash is used.

After all, one can always easily run other program from these files.