test scripts overhaul

Rewrite TESTonce to do only one thing (run a test with given parameters)
but do it well. Split TESTrun.sh into functions and extend it to do only
a specific test if requested. Justify format of the test results and
move most of the test results printing from TESTrun.sh to TESTonce.
LMPv1: make the "-v" test GCC-specific (GH #333)