[views] csvexport accept an empty rset (closes #4236928)
When you tried to apply the 'csvexport' view on an empty rset, the view
couldn't be selected and you got a HTTP 500 error.
Also add two new test cases.
action box
Area visible in the upper left column. You have a list of available actions on the entity. The most frequently used entry is `modify`.
object
All element created in the application
Example: project, ticket, user, ...
relation editing module
HTML widget that let you define new relations amongst objects.
relation
It's a kind of 'smart' link between 2 objets of the application. It has a specific sense that determine dynamic behaviour and add a new logic of the content.