Improve page depth counting efficiency
Improve page depth counting efficiency

We don't need to listify a re.finditer result in order to count
the number of forward slashes that appear in a page title - all
we have to do is use the built-in function string.count(substr).

Change-Id: Ia457c837380f4681046bca64243b826e3ae7a302

jayvdb/pywikibot-core,hasteur/g13bot_tools_new,hasteur/g13bot_tools_new,wikimedia/pywikibot-core,npdoty/pywikibot,Darkdadaah/pywikibot-core,PersianWikipedia/pywikibot-core,npdoty/pywikibot,happy5214/pywikibot-core,hasteur/g13bot_tools_new,Darkdadaah/pywikibot-core,jayvdb/pywikibot-core,wikimedia/pywikibot-core,happy5214/pywikibot-core,magul/pywikibot-core,magul/pywikibot-core