We still want user to create PREFIX dir themselves, but the message was
unclear about what is actually wrong.

The existence test is done on next line, and with -f in place,
canonicalization or non-existent PREFIX leads to empty PREFIX which
makes the next message confusing

Use MKIT_INI to specify path or default to mkit.ini in $PWD

 *  Move targets to mkit/mkit.mk,
 *  make `mkit/make` and rest of mkit use MKIT_DIR for own path.

 *  Split to functions more properly,
 *  save calling of head,
 *  save calling of perl,
 *  keep own data at one place,
 *  make _pretty__echo more readable.

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.