Small enhancements of the test-lib.sh

  Here is a 2-patch series to enhance the test-suite so that the flood
is easier to follow to the eye.

  The first patch is a rework of the previous one I sent, and implements
suggestions that were made to me.

  The second add a --quiet option that basically stops the flood about
all the test that just pass, and only let the name of the master
t####foo.sh script be printed, and the summary of its test (and the
occasional spurious outputs the testsuite does).

  This "series" is available as ph/testlib on my
git://git.madism.org/git.git

Cheers,