First of all thanks a lot for this great library! It makes working with the GitLab API a real breeze.

As the title of the issue says: It would be great if support for the single issue API could be added. It probably is one of the lesser used APIs (in fact, I never was in need of it until exactly now 😉). In my special case, I need to find the web URL for an issue after it has been moved. Issues that have been moved have the moved_to_id attribute set to the destination issue's id. However, currently there seems to be no other way to get a single issue by its id than this API.

Thanks a lot!