there is not longer needed the manualy created blacklist of copied files;
also no need to remove symlinks from clone subdir
use "tar --checkpoint-action=exec="echo -n \".\"" instead of
"awk '{ ORS=\"\" ; if (++nlines\%50 == 0) printf \".\"; fflush() }'";
we are interested into the return code from tar, e.g. not-enough disk space
Add --bzip2 and --xz options to select the compression. Both options
can be used togetger to generate both types of tarballs in one call.
XZ compession is used by default.
Also renamed "lo*build" strings to "lo*core" to fit the current name
of the top level source directory.
