Bug fixes and overhead reduction Added the --problem/-p option. (WARNING: not the same as the -p option of test.py 1.x.) The problem names supplied are not validated. Added zip_longest to compat.py. Experimental: problem names are now _always_ printed for multi-problem sets. Overhead: Escape presses are now checked only once every .15 seconds (at least kbhit() on Windows is very slow). Overhead: sleep(0) is now called in the time-control-and-Escape-watching loop (at least on Windows, it immediately transfers control to some waiting thread). Bug fix: compat.py now overwrites built-ins only while including testconfs (--help was broken in Python 2). Bug fix: ReadDeleting in config.py now closes the file it opens (especially important on Windows, where open files cannot be deleted). Bug fix: added callable to compat.py (it is absent from Python 3). Bug fix: the default (built-in) output validator now properly handles unwanted trailing data. Bug fix: testconfs in custom archives no more raise NameError. Bug fix: if a validator program cannot be launched, CannotStartValidator is now raised instead of the fatal OSError.