We're jumping straight up to v1.0!

Small changes

Set the kernel log level to 0 when in the menu system, then restore it to the original value on boot
Reverse sort the kernel list, so the most recent is always first
Add an initial chroot helper script, zfs-chroot for the recovery shell. It can be invoked as zfs-chroot pool/ROOT/BE.
Set the default config path in generate-zbm to /etc/zfsbootmenu/conf.d
Allow the EFI stub file to be defined in config.ini
Optionally read the kernel command line from /etc/default/zfsbootmenu

Large changes

Clean up or whitelist all issues in zfsbootmenu-lib.sh, zfsbootmenu-preview.sh and zfsbootmenu.sh noted by shellcheck.
Support entering a custom kernel command line via alt-c on the main menu. The input line is pre-filled with the command line that would have been used on the next boot, for that environment. This command line is NOT persisted between reboots, it's simply here to let you recover an unbootable system.
Add support for reading the kernel commandline from the ZFS property org.zfsbootmenu:commandline. This property is now considered the default/primary source of truth for the kernel command line - it takes precedence over /etc/default/zfsbootmenu and /etc/default/grub.

A big thank you to @ahesford for his code contributions and testing leading up to this release!