Align behaviour of expect_references with docs

[MatthiasValvekens]

Passing expect_references=True to verify(...) now results in a list of verify_results, irrespective of the number of references in the signature.

Fixes #278.

[MatthiasValvekens]

Thanks for the swift review! You might have to do the honours of merging the PR yourself, though--I don't have merge access here :).

[kislyuk]

Thanks for the swift review! You might have to do the honours of merging the PR yourself, though--I don't have merge access here :).

Would you like to? :)

You've done a great job maintaining python-pkcs11, would be happy to have you on board here if interested.

[MatthiasValvekens]

Thanks! I'd be happy to help out here and there, but chances are that it won't be to the same extent as for python-pkcs11. The main reason is bandwidth (as always). In addition to that, my exposure to python-pkcs11 as a dependency has always been quite significant, so I had a very direct incentive to fix stuff there, and I also was much more familiar with the lib's internals already.

As for signxml: my pyhanko lib will have an optional dependency on signxml starting in the next release, so chances are that I'll wind up contributing more bugfixes in the future. But things like helping with clearing the backlog of issues/open PRs/etc. probably isn't in the cards in the short/mid term.

Up to you to decide if making me a collaborator on this project makes sense given that context. Collaborator or outside contributor: I'm fine with either :).