Remove object as base class for MutableChain
Remove object as base class for MutableChain

Plus some minor styling adjustments

scrapy/scrapy,dangra/scrapy,starrify/scrapy,dangra/scrapy,dangra/scrapy,elacuesta/scrapy,eLRuLL/scrapy,scrapy/scrapy,pawelmhm/scrapy,pablohoffman/scrapy,pablohoffman/scrapy,eLRuLL/scrapy,starrify/scrapy,pawelmhm/scrapy,elacuesta/scrapy,pablohoffman/scrapy,elacuesta/scrapy,scrapy/scrapy,pawelmhm/scrapy,eLRuLL/scrapy,starrify/scrapy