At the moment, the ability to select the kernel with which to boot is
implemented only for grub (grub-pc, grub-efi, ieee1275boot).
note that renamed STAGE1_KFLAVOUR to STAGE1_KFLAVOURS, as multiple
kernels can now be added.

doc/archdep.txt was the reason to look closer,
and some other files needed a bit of facelift
by now too (would be better to do that in sync).

Another minor facelift:
- s/ALT Linux/ALT/gc (where applicable);
- s/7.0/8.0/g;
- 2017;
- e2k;
- links.

It wasn't clear enough what the whole tracing affair is for;
thanks ykos@ for spelling it aloud.

0.6.3 has introduced some changes that were deemed incompatible
with t6/p6 branches; it should be possible to restore compatibility
at least for non-EFI images but the effort required hasn't been
up for grabs so far.

See also https://bugzilla.altlinux.org/30474

stage2 has been thinking it's synonymous with propagator
and used to usurp kernel's belongings either; carefully
tear scripts apart so that kernel feature makes sure
initrd gets generated, and stage2 (which is still all
about propagator) cares for its bits.

These have been proofread somewhat to correspond
to the current state of affairs; a missing one
was added for fonts feature.

Folks have been wondering already whether e.g. t6 breakage
qualifies as a bug; it does indeed unless the "broken" part
depends on the features not available with that branch yet,
e.g. EFI support.

That is, p6/t6 continue to use 3.81 (while providing 3.82
alongside with it), and Sisyphus has moved to 3.82 before
p7/t7.  We support both versions by now.

Docs should live happily together, after all,
and toplevel should be more or less uncluttered :)

Adjusted/rewrote as appropriate as well.

Status updates and readability tweaks all over the place.

The purpose is being able to examine particular target interdependency
graph for a given image having been configured to avoid convoluted
dependencies (loops in particular).

The implementation is based on SHELL hook hint by John Graham-Cumming:
http://cmcrossroads.com/ask-mr-make/6535-tracing-rule-execution-in-gnu-make

From what I've read so far, most of the code should run on 3.80;
there seem to have been some bits that are dependent on 3.81
features, but there is not a bit that depends on 3.82+ features
so far.

doc/variables.txt was missing the already-existing BUILDLOG
variable description, and ARCHES got added during multi-target
toplevel rewrite.  Other minor fixes come as appropriate.

This is quite a large-scale change since mkimage-profiles got used to
baking distributions over the last year, and virtual environments are
quite different, so e.g. image.in/Makefile had to be split in two with
the main part of it moved into features.in/iso/lib/.

Short overview:

- features.in/Makefile: lib/ support
  (supporting VE images requires dynamic modifications
  to image.in/Makefile before starting the build;
  the most natural way to achieve that seems to use
  features mechanism along with makefile include dir)

- packaging format related part moved into features.in/pack
  (should be better prepared for diversity either)
- features.in/iso renamed to features.in/build-distro
- features.in/ve  renamed to features.in/build-ve
  + NB: these could not be merged as e.g. features.in/build
    due to completely different script hooks

- lib/image.mk renamed to lib/build.mk
- image, config, log postprocessing moved downstream
- added a sort of a topping in the form of lib/sugar.mk
- assorted style fixups (like ifeq usage)

- clean.mk: reliability fix (the problem was observed by Oleg Ivanov
  and me too but finally it did get the attention quantum)

- reviewed, updated and extended docs
  + QUICKSTART: should be[come] a step-by-step guide
    (thanks Leo-sp50 for prodiving feedback)

Somewhat more uniform style and a few additional bits.

Implementation based on m-p-d::profiles/scripts.d/03-syslinux
(but heavily modified for m-p of course)

- introduced generic stage2 subprofile (non-standalone)
- ported installer and rescue over to stage2/{install2,rescue}
- initial stage2/live (needs more work for sure)
- use make-initrd-propagator
- updated and somewhat extended doc/

NB: mind #26133, #26134