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)

install2 cleanups:

- functionally indifferent ones: particularly, install2/*/98system's
  "mkdir -p /image" was superfluous as it was done by that time already
  by sub.in/stage2/image-scripts.d/00stage1

- taken apart, prepared for tags: so far it's a mostly moot change
  since the installer cleanup scripts themselves are mostly the same as
  preceding 90cleanup was (with some additions corresponding to recent
  kernel development); it's still unclear what the mechanism for
  configuring the cleanups in effect will be, either directory/package
  regex lists or tagged scripts excluded from execution by yet another tag

fixes:

- image.in/Makefile: fix metadata related test; the actual test was
  assuming that stage1 kernel means installer, which is not the case
  since generic stage2 introduction; oh well

- 85cleanup-lowmem: a "_" too much was the culprit in destroying the
  needed translations along with those deemed superfluous; thanks go to
  Oleg Ivanov and Lenar Shakirov for finding the bug and proposing the
  fix altogether

additions:

- features.in/Makefile: reworked help target; it was rather inaccessible
  due to BUILDDIR normally undefined at the time of direct make
  invocation, and BUILDDIR is normally defined during normal builds
  anyways so let's try it this way.

- README++

daydreams:

- 01-genbasedir: we should drop bzip2 compressed pkglists some day
  but see genbasedir and apt-cdrom first, 90-pkg.sh (alterator-pkg)
  will fail miserably otherwise

- better *_LISTS printout
- somewhat cleaner .base comments
- more comprehensible git log messages
  + special handling for complex subprofiles
  + no need to commit build.log ;-)

This was pulled from mkimage-profiles-desktop as is,
and so far is useless (addons, ltsp are out of scope yet).

When reintroduced, it'd better be done as a separate script.

This looks a bit weird (two subprofiles become a bit more
tightly coupled) but in fact install2 does depend on stage1,
and if stage1 doesn't create squashcfg.mk then install2 is
just fine with defaults (provided they fit the installer kernel
used).  A proper mkimage test infrastructure might be handy though.

Also there:
- 01-initfs: partial cleanup (bootsplash is obsolete anyways)
- regarding 03-test-kernel's errorlevel test:
  if 0, 1 and 2 need to be distinguished, "!" MUST NOT be used
  as it negates so that 0 becomes 1 and the rest becomes 0

- image.in/functions.mk: rework kpackage()
  + it takes two arguments explicitly now: this adds some noise
    for "generic" invocations but is rather less messy with recently
    introduced STAGE1_KFLAVOUR (which in its turn is rather cleaner
    than messing with KFLAVOURS, especially since soemthing changed
    in presumably apt and we can't rely on kernel packages being
    installed in the order formed).
- BUILDDIR/DEBUG related fixes
  + Makefile: BUILDDIR initialization moved to distro.mk
- build.log += git info

- s/stage2/install2/g
- added pkg/lists
- initial README (ru_RU.KOI8-R)
- mkimage topdir is in image.in/, really (off-tree build)
  + initial bin/mktmpdir
  + BUILDDIR (works)
- s/cd/iso/
- drop --with-distro (considered harmful)