* Remove duplicate config.txt copy statement
* Use static cmdline.txt file
Instead of dynamically creating cmdline.txt use a static version of it.
This aligns with other boot loader/firmware configuration files and makes
it easier to customize the file per board.
* Enable some useful kernel configurations
* Add xe-guest-utilities for better Xen support
Add guest utilities and make sure the Xen guest daemon gets started
when running under Xen virtualization.
Using console focused virtualization environments such as virsh having
a serial console is the easiest way to interact with a virtual machine.
It also saves resources since no video memory needs to be allocated.
Enable serial console besides tty1 by default.
Note: The bootloader as well as the kernel shows its boot messages on
all consoles. However, only the last console is mapped to /dev/console,
which systemd is using to show service startup messages. Putting tty1 as
last console makes sure that systemd messages are still shown on the
console screen.
Virtual Disk images are often used on Windows and/or Mac platforms where
xz is not a widely known file ending and also not supported by dafault.
Use zip which is much better known.
Keep using xz for boards since those are not meant to be extracted by
users but directly used in Etcher. Also keep using xz for qcow2, since
qcow2 is mostly used on Linux platforms where xz is available by default
and zip usually needs an extra package.
* Rename Intel NUC machine to Generic x86-64
The Intel NUC machine has evolved and supports various x86-64 machines
today. Rename the board.
Note that this does not address the migration issue. This will be
handled separately.
* Update Scripts/Documentation
