Not sure why I did it in the first place.

This disables user from choosing different mode; behave as other
printers.

/dev/stdin will be treated as normal file, albeit `test -s` would detect
it as non-existent.  '-' will cause STDIN to be used as wellm but will
omit header.

exit does not work as we want in subshell, so we need to exit higher.

Introduced by fefce4a0, typo invalidated catfun and ffdoc

In mkit's world, last change before release (ie. the commit that gets
tagged) must be nothing but version bump in "config.mk"

Other checks that rely on version number that is derived from this tag
would then give weird messages.

A first version that is versioned

IOW, it's not guaranteed that once we are in git repo we can always see
the tag.  VERSION should be reliable, though.

So that one can still build without having it set properly.

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.