[selectors] match_kwargs and match_form_params selectors both accept a new `once_is_enough` argument (closes #1990438)
also fix docstring of match_exception and references to selectors in the book.
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.