* Mention 'target x86_64 only'.
* Better detection of the grub-mkimage location.
* Check availabilty of x86_64-efi grub modules.
* Actually exclude our own boot loaders from the menu.
* Check that the boot applications be for x86_64, although this should
  be redundant with the + pf PE32+ images.
* Update the partition name in the boot menus if need be.
* Cosmetic enhancements of the UI.