This change is done to reduce ambiguity in some cases;
the previous intention has been to ease navigation when
staying in a particular directory, now it's been changed
in favour of convenient toplevel `git grep' in fact.

Both variants have their pros and cons, I just find myself
leaning to this one by now hence the commit.  Feel free to
provide constructive criticism :)

Some path-related bitrot has also been fixed while at that.

Actually the issue was worse in general: *_PACKAGES
weren't quoted when put into .base thus resulting
in a potentially broken echo command (silent one).

The macro scheme used was overgeneralized; stuffing
quoting differentiation into it was doable but ugly
(unless one is able to pass an unquoted quote sign
as a function's parameter in some elegant manner),
let's just make it straightforward.

The generated comment went wrong when the script was renamed.

It was missing THE_GROUPS rather completely (but should not care for
LIVE_GROUPS -- are these useful anyways?); thanks sem@ for spotting.

An initial draft of it was done half a year ago but several tricky
thingies had kept the code from showing up as it was rather brittle
and incomplete.

This implementation involves quite a few changes all over the place
but finally works good enough for live and installer images.

Please pay attention to the versions of these packages:
- installer-feature-setup-plymouth (0.3.2-alt1+)
- branding-altlinux-sisyphus (20110706-alt2+ if used)
- plymouth (0.8.3-alt20.git20110406+)

See also:
- http://www.altlinux.org/Branding
- http://www.altlinux.org/Plymouth

This further refines the modular build by making
metadata being a clearly separated feature rather
than having to rely on runtime tests, and also by
moving the code which cares for kernel bits of base
installation (.base list) in a feature of its own.

There's more to it but let's get the ball rolling first.