NOTE: This was unintentionally squashed so some details were lost
* Major updates to build_linux to support the current archiso scripts
* Most customize_airootfs.sh code has been moved elsewhere
* Using static files or links where possible
* Generating other files as needed in build_linux
* Syslinux configuration has been simplified
* Dropped i3
* Dropped rxvt-unicode in favor of termite
* Font rendering broke one too many times
* Dropped NetworkManager in favor of iwd/systemd-networkd