[Which test scripts are executed]
---------------------------------
"run-tests.php" ("make test"), without any arguments executes all
-test scripts by looking extracting all directories named "tests"
+test scripts by extracting all directories named "tests"
from the source root and any subdirectories below. If there are files,
which have a "phpt" extension, "run-tests.php" looks at the sections
in these files, determines whether it should run it, by evaluating