Refactor out PositionableEndpointView as a parent of ParametricEndpointView and FollowingEndpointView
Implement FollowingEndpointView
Merge branch 'develop-frontend' into feature/issue-350-a-following-endpoint-is-needed-for-the-dialogue-screen

Conflicts:
	go/base/static/js/test/tests/components/plumbing/endpoints.test.js
Merge branch 'develop-frontend' into feature/issue-350-a-following-endpoint-is-needed-for-the-dialogue-screen