Introduce EntryEndpointView and ExitEndpointView to the dialogue screen
Prevent connections from being made on the same dialogue state
Tests for dialogue screen bad connection handling
Merge branch 'develop-frontend' into feature/issue-443-users-should-only-be-able-to-connect-exit-endpoints-to-entry-endpoints-on-the-dialogue-screen

Conflicts:
	go/base/static/js/src/campaign/dialogue/diagram.js
	go/base/static/js/src/campaign/dialogue/states/end.js
	go/base/static/js/src/campaign/dialogue/states/freetext.js