PURPOSE
Check square-bracket-style constructor.
Also checks constructor called with a hashref (works, but not officially supported).
Tests that objects overloading both hash and array are considered to be hashrefs by the constructor, not arrayrefs.
AUTHOR
Toby Inkster <tobyink@cpan.org>.
COPYRIGHT AND LICENCE
This software is copyright (c) 2012 by Toby Inkster.
This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.