This feature complements the live image of the second stage with installation
image-specific settings and scripted hooks.

It is recommended to connect using +live-installer to ensure that a typical set
of installer-related features is included.

Unlike the install2 feature, a separate image of the second stage of 'altinst'
is not built, but the live image is supplemented with installer packages in
order to reduce the total volume of the iso image.

Installation consists of two stages:
1. The live image is unpacked, as in livecd-install
2. Install additional packages BASE_PACKAGES and package groups THE_GROUPS as in install2.

Unlike install2, only those packages that are not in the live image are placed in the main repository. This is how the size of the iso image is reduced.

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

As it happens, I've stumbled upon a successfully built image
with alterator-grub in BASE and lilo in install2's installer-steps.
Of course the installer bailed out after dealing with packages :-/

Thanks Leo-sp50 for pointing out the (hopefully) right direction.

- 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

NB: needs installer-distro-altlinux-generic = 6.0-alt2
    as it doesn't require alterator-grub indefinitely