ENH: Turns InteractiveConnectedComponentsUsingParzenPDFs into editor effect.

Change-Id: I008bf01b7b259c228e4b82ebe7a8c466a8eb55db

Also adds 21x21 icon for editor extension

Change-Id: I917ed2e5702497299a9c5578c0a502063bacd98f
Merge branch 'master' into add-editor-extension-tmp

Conflicts:
	SlicerModules/InteractiveConnectedComponentsUsingParzenPDFs/InteractiveConnectedComponentsUsingParzenPDFs.py

Change-Id: I47eb3967bd0f800f1ee22c1f06bd347dbe97018c
Merge topic 'add-editor-extension-tmp'

7fe1c4b Merge branch 'master' into add-editor-extension-tmp
a6ac2ca ENH: Turns InteractiveConnectedComponentsUsingParzenPDFs into editor effect.