English parsing: allow role inheritance without article.
Sharing details: display error when role can not be guessed.

Falling back to the text from the view does not really make sense
and breaks things afterwards.
Extract and extend role inheritance helpers into utils.

The role inheritance functions should be publicly usable.
This also improves names and documentations for the helpers.
Describe roles: follow and resolve inherited roles.
Merge pull request #39 from 4teamwork/jone-sharing-details-role-inheritance

Sharing describe roles: resolve role inheritance