Respect content/node access permissions

You know, I'm really not sure! I don't have my head wrapped around the entire codebase yet, but I will check into that for you.

This is only a partial answer: the module currently checks "!empty($node->status)" which means it won't post to Twitter if the node is not published. However, it's not checking to see if (for example) an Anonymous user can view the node, so I don't think it will correctly detect a published but "private" node.

Maybe this use case could be addressed by selecting a user role that should be able to see a node in order to control whether to post to Twitter, defaulting to Anonymous. This seems like an edge case, so I'm not positive whether it'll be addressed in the way I'm describing, but I do think there are likely to be other issues around this.

The exact functionality will need to be fleshed out, but URLs should (optionally?) only be tweeted for content accessible to Anonymous users.

Would need to be configurable (can envisage a PPV site not wanting to require anonymous access to promote new content).