Comment 0 for bug 189630

This is useful to support distros that do not ship a Live CD as well as ensuring consistent behaviour for similar boot parameters. The d-i changes should affect only hdmedia. The required changes are:

1) "find_iso" parameter in lupin/casper is renamed to "iso-scan/filename"
2) iso-scan in d-i is modified to properly use the filename parameter. See http://paste.ubuntu-nl.org/54997/ for a preliminary iso-scan "patch"
3) "debian-installer/custom-installation" is renamed to "scan-custom-installation/foldername" (pending colin comments)
4) a d-i udeb is added to scan for custom-installation folder and take appropriate actions (particularly preseeding off custom-installation/preseed.cfg)
5) Within wubi, use the hdmedia initrd/kernel whenever an alternate ISO is involved.