[login ui] cleanup and somewhat bw compat

[selectors] move selectors according to their type, add missing ones to documentation

[forms] remove dead code and simplify inlineviews creation remove AutomaticEntityForm.should_inline_relation_form which is not used anywhere and comes from a time where uicfg did not exist. remove test for "force_<rtype>_display" presence in req.form to determine whether or not the inline creation form should be displayed.