LUKS support in debian-installer

> the installer doesn't seem to support it at this time, only dmcrypt sans luks

It does. :-) 

LUKS has been supported together with loop-AES and plain dm-crypt since before the first
released version (Debian etch).

I see where we might be creating a different perception:

In the installer menu we call the encryption system "dm-crypt" [1]. Depending on the key type
it will create a LUKS partition ("Passphrase") or a plain dm-crypt mapping (volatile one-time
"Random key").

[1] Calling it dm-crypt is technically correct - LUKS really is dm-crypt plus key and
parameter management, but it completely hides the fact that some key types imply a LUKS
header.