numeration for preserved partions

[Edgar Fuß]

> Testing would be much appreciated, didn't get around to do any testing myself yet.
It doesn't work because the unit conversion that's done in between overwrites the regexp results.
I fixed that by inserting
	my $flags = $5;
(resp. $3) just before the 
	# convert the units, if necessary
line and using $flags instead of $5/3 below.

Looks like :resize coudln't have worked before, too.

My fixed version works (we re-factored the patch for FAI stable).