[bugfix] Do not ignore -pattern option in imageharvest.py
[bugfix] Do not ignore -pattern option in imageharvest.py

-pattern option toggles image_url to True.
This must not be overridden in run_bot function.

Also fix the compat's [s]top option to break uploading
which was never reached currently.

Other improvements:
- shorten "if url == '':" to "if not url:"
- shorten assignments to minimum, maximum and basicdec
- use a slice generator for ilinks if image_url is True
  instead of filling a list

Bug: T224714
Change-Id: Ie39862b1ae6f35bb5ab952e78c734c1db96ef06c

PersianWikipedia/pywikibot-core,wikimedia/pywikibot-core,wikimedia/pywikibot-core