work-a-round; prevent subster.py to crash on wikidata when refs cannot be set
improvement; introduce parameter '-page' for debugging/testing purposes

Change-Id: I42aa1769bb0b053e2f8134ab1177d970cda28ee3
Merge "work-a-round; prevent subster.py to crash on wikidata when refs cannot be set improvement; introduce parameter '-page' for debugging/testing purposes"