test conflicting kinds

From http://usejsdoc.org/tags-kind.html:

> In the case of tags with conflicting kinds (for example, using both @module, which sets the kind to "module", and "@kind constant" which sets the kind to "constant"), the last tag determines the kind.
>
> Conflicting @kind statements:
>
> ```
> /**
> * This will show up as a constant
> * @module myModule
> * @kind constant
> */
>
> /**
> * This will show up as a module.
> * @kind constant
> * @module myModule
> */
> ```

documentation.js should:
- issue a warning in this scenario
- let the last tag determine the kind