With this change, we simplify the created initrd image. Kernel
modules and firmware are added by make-Initrd itself. The layer
in Initrd is now one. It also allows you to unifyed configs for
bootloading with propagator and bootchain.
Config files for refind and elilo is creates in mkimage, so have
to copy initrd.img in efi/boot/ with the name full.cz.

This will allow for ISO, writed on flash, disable gfxterm and
enable serial console, if necessary. For EFI only.

Example:
GRUB_TERMINAL='console serial'
GRUB_SERIAL_COMMAND='serial --unit=0 --speed=115200'

Use a more reliable way to identify the theme grub.

Not need to configure all network interfaces. propagator and bootchain
configure one network interface detected on network boot.

The 'splash=0' parameter not only disables splash, but also switches
to tty5 on which plymouth is supposed to run. This looks like a bug
in propagator. 'nosplash' is also a general parameter for propagator
and make-initrd.

This parameter needed for bootloading with initrd-bootchain.
there are currently no network configuration dialogs when booting
with initrd-bootchain.

For install2, this is needed to work around error 99-cdrom.sh with method:cdrom.
The error shows up with make-initrd-bootchain, but not propagator, as lowmem is
enabled for propagator in this mode.
For rescue, the point is that the latter has become quite large, so by default
it would be better that way.

For use them separately.

Top item is no need to set a default. Also, this is no longer
possible, as some items are not available for all grub variants.

If GRUB_UI variable is set, the gfxterm config will be added, which
in turn will lead to a build error on an unsupported architecture.

More accurate name of the menu item.

Add multiple kernels support and initrd.img support instead full.cz.

1. Didn't work before because the variable was not exported.
2. Fixed the logic broken by the introduction of support for saving
the selected item on the FAT partition.

If the ISO image has a FAT partition and the image is written
to a flash drive, then it is possible to write to this partition
of the flash drive.
This is necessary, for example, if the user
does not want to install the system, but wants to constantly work
in LiveCD mode with or without recording sessions.
In order for this code to work, you need to make changes
to the FAT partition of the image on the flash drive:
Add the 1st line to the grub.cfg file:
set pfxfat=${prefix}
Write a 1kb file grubenv.
If grub.cfg contains a line like '^default=id',
then the read value is not used.

This prepares the ability to write and read
the default menu item from the grubenv file.
If grub.cfg contains a line like '^default=id',
then the read value is not used.
Setting the default menu item from the grubenv file
will be indented inside the 'if' optator and therefore
does not match the '^default' pattern.

Just a cosmetic fixup (until not paired up with translations):
"2nd" means "second", "1st" meant "first".

use/grub/localboot, use/grub/sdab similar to use/syslinux/localboot,
use/syslinux/sdab.

Note: syslinux --install needed /proc, so:
@$(call set,GLOBAL_HSH_PROC,1)

See-also: mkimage/doc/README.ru

memtest is not part of syslinux.
Also replace tabs to spacebar.

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.

This reverts commit 5848ae70.