[PATCH] Build is not reproducible

Because of the use of DATE, TIME and the generation of the default skin (tar.gz compression) builds are not reproducible. Something desirable for a lot of reasons to a Linux distribution.

The DATE and TIME thing can be easily fixed through sed without too much risks. But the default.vlt file generation requires of a patch that would be better upstream.

The problems are: a) gzip stores the modification time of the tar file b) tar stores the files in a random order

The patch generates the file lists through find and sort and uses gzip's '-n' option to avoid the timestamp. It makes no change for general use but helps whoever wants reproducible builds.