Adding option of not deleting the old cat
Adding option of not deleting the old cat

(update from compat),
- pep8 changes
- replace pywikibot.output("warning") with pywikibot.warning("")
- synchronize with compat

Change-Id: Ia555c20e6360c0c4bcb603af6f76b39fc08d3e88

hasteur/g13bot_tools_new,smalyshev/pywikibot-core,xZise/pywikibot-core,PersianWikipedia/pywikibot-core,Darkdadaah/pywikibot-core,TridevGuha/pywikibot-core,VcamX/pywikibot-core,wikimedia/pywikibot-core,magul/pywikibot-core,darthbhyrava/pywikibot-local,valhallasw/pywikibot-core,magul/pywikibot-core,hasteur/g13bot_tools_new,npdoty/pywikibot,h4ck3rm1k3/pywikibot-core,jayvdb/pywikibot-core,npdoty/pywikibot,trishnaguha/pywikibot-core,icyflame/batman,wikimedia/pywikibot-core,Darkdadaah/pywikibot-core,happy5214/pywikibot-core,h4ck3rm1k3/pywikibot-core,jayvdb/pywikibot-core,hasteur/g13bot_tools_new,emijrp/pywikibot-core,happy5214/pywikibot-core