Added LUKS Unlock dialog.

Also, bug fixeeeeeeeeeeeeeeeeeeeeeeeeeeeees.
partdisks: add cipher and key-size selection for the to-be-encrypted volumes (using seeds).

partdisks: default to aes-xts-plain64 (cipher) and 512 (key-size)

linstaller.py: resolved a seed parsing bug which involves values with an :
partdisks: made the fill checkboxes working
bootloader: now the user can force a device or skip the bootloader installation (via seeds)

bootloader/front: glade: if LVM, assume root = /boot if it's isn't a LV, or skip installation

BUG FIXES.
4.91.0
Merge branch 'devel' into debian-devel
4.91.0