QT5 is now the default.
Python3 is now the default.
Fixes for 18.04's recent kernel early microcode changes breaking customizer's UUID extraction from the initrd.
18.04 includes /usr/bin/unmkinitramfs in initramfs-tools-core, but earlier versions may not.
It's included in this release's artifacts, just to save someone a hassle.
Stick it in FileSystem/usr/bin/unmkinitramfs for releases earlier than bionic that have gotten microcode updates.