deleteEqualMessages: Include list of pages in dry run

Also clarify that the talk page number is in addition to the
other number. So it says "10 pages are equal (+ 2 talk pages)"
instead of "10 pages are equal (2 talk pages)".

Document better that the default is a dry run.

Change-Id: I95edb08d7b92c393ed226bef2575e52a6135f8df
Merge "deleteEqualMessages: Include list of pages in dry run"