[session] should be _cw, not req

[primary] use a new rtypevid flag in primary view display controller, allowing to tell the view for a non final relation should be called as an attribute view (eg, not on the target rset)

[cwprops] fix callable vocabulary of cwproperties which were inconsistently called. No more argument, should now simply return a list of (untranslated) values

[vreg] rename select* object id argument to avoid name clash with arbitrary kwargs, just in case...

[primary] refactor primary view handling of relation's label to properly handle label optionaly specified in dispctrl (no more default set) and use contextual translation by default. Also, consistent handling in attributes, relations and sideboxes section. Introduce new support_args function to use when possible instead of try/except TypeError.

backport stable