[IMPR] set -ignore option to CANCEL.MATCH by default
[IMPR] set -ignore option to CANCEL.MATCH by default

- set -ignore option to CANCEL.MATCH by default to ignore ISBN errors
- update module doc string
- simplify arg parsing

Bug: T108446
Change-Id: I0d7650d79262b38a512b360a0ff93069b35a5e00

wikimedia/pywikibot-core,wikimedia/pywikibot-core