h.remove_url_param with the minimal set of parameters:

h.remove_url_param("q")

will throw an error on the organization.read page(not only here). Because internally it gets current blueprint and view (g.controller and g.action) and tries to build the URL h.url_for(blueprint + "." + view). And as long as the given blueprint requires extra arguments (package_type for dataset pages, group_type/is_organization for group pages, id for organization.read page, etc), this will fail. User has to do something like

h.remove_url_param("q", extras={"is_organization": group_dict.type, id=group_dict.id, "group_type": group_dict.type})

While it is perfectly ok from the clarity point of view, it requires every developer to know CKAN internals and these extra parameters. And it makes the given helper too fragile. In addition, the extras parameter is optional, so there may be some expectations, like
whenever I'm using h.remove_url_param("q") in the simplest form, I expect q to be removed from the CURRENT URL, whatever it is

This PR takes all the extra parameters required to build the current URL and adds them only when neither controller nor action nor extras argument is present. I.e, only when the user trying to modify the current URL.

PS. And it also updates toolkit.get_endpoint. Now it won't raise RuntimeError in CLI. Instead, its returns None, None, which is quite safe, I think.