Add a PATH

On *BSD, an empty path triggers a "Insecure $ENV{ENV} while running
with -T switch" error. This is a perlbug we have to work around.
Compare configuration case-insensitively

Otherwise perl on Windows might get confused. E.g.
http://www.cpantesters.org/cpan/report/8b15ea37-728c-1014-930b-033393e8ee67
Allow for executable extension in tainted test
Fixed up documentation
v0.010

          Add a non-empty PATH, to make *bsd happy
          Compare configuration case-insensitively, to make Windows happy