MAINT: Initialize Portfolio object with default values for attributes
MAINT: Initialize Portfolio object with default values for attributes

instead of no attributes at all

florentchandelier/zipline,cmorgan/zipline,DVegaCapital/zipline,keir-rex/zipline,wubr2000/zipline,gwulfs/zipline,iamkingmaker/zipline,keir-rex/zipline,euri10/zipline,jordancheah/zipline,otmaneJai/Zipline,zhoulingjun/zipline,humdings/zipline,morrisonwudi/zipline,CDSFinance/zipline,dmitriz/zipline,bartosh/zipline,wilsonkichoi/zipline,quantopian/zipline,kmather73/zipline,semio/zipline,bartosh/zipline,CarterBain/AlephNull,jimgoo/zipline-fork,MonoCloud/zipline,aajtodd/zipline,magne-max/zipline-ja,umuzungu/zipline,AlirezaShahabi/zipline,quantopian/zipline,AlirezaShahabi/zipline,iamkingmaker/zipline,gwulfs/zipline,euri10/zipline,zhoulingjun/zipline,Scapogo/zipline,florentchandelier/zipline,sketchytechky/zipline,enigmampc/catalyst,dkushner/zipline,stkubr/zipline,dkushner/zipline,kmather73/zipline,nborggren/zipline,ronalcc/zipline,ChinaQuants/zipline,MonoCloud/zipline,wubr2000/zipline,grundgruen/zipline,StratsOn/zipline,mattcaldwell/zipline,wilsonkichoi/zipline,magne-max/zipline-ja,YuepengGuo/zipline,otmaneJai/Zipline,chrjxj/zipline,grundgruen/zipline,michaeljohnbennett/zipline,jimgoo/zipline-fork,Scapogo/zipline,humdings/zipline,erikness/AlephOne,semio/zipline,sketchytechky/zipline,YuepengGuo/zipline,ronalcc/zipline,CarterBain/AlephNull,erikness/AlephOne,StratsOn/zipline,enigmampc/catalyst,ChinaQuants/zipline,alphaBenj/zipline,aajtodd/zipline,DVegaCapital/zipline,mattcaldwell/zipline,jordancheah/zipline,chrjxj/zipline,alphaBenj/zipline,dhruvparamhans/zipline,joequant/zipline,umuzungu/zipline,cmorgan/zipline,joequant/zipline,nborggren/zipline,CDSFinance/zipline,dhruvparamhans/zipline,dmitriz/zipline,stkubr/zipline,michaeljohnbennett/zipline,morrisonwudi/zipline