use _coeff_isneg in str._print_Mul
use _coeff_isneg in str._print_Mul

    This also includes some pep8 edits.

abloomston/sympy,oliverlee/sympy,sunny94/temp,shipci/sympy,rahuldan/sympy,sahilshekhawat/sympy,kevalds51/sympy,VaibhavAgarwalVA/sympy,ahhda/sympy,Vishluck/sympy,MridulS/sympy,Designist/sympy,kaichogami/sympy,ahhda/sympy,atreyv/sympy,Mitchkoens/sympy,hargup/sympy,pbrady/sympy,Arafatk/sympy,Mitchkoens/sympy,madan96/sympy,AunShiLord/sympy,ga7g08/sympy,moble/sympy,chaffra/sympy,jerli/sympy,souravsingh/sympy,amitjamadagni/sympy,lidavidm/sympy,farhaanbukhsh/sympy,ahhda/sympy,dqnykamp/sympy,jaimahajan1997/sympy,beni55/sympy,sahmed95/sympy,mafiya69/sympy,Shaswat27/sympy,MechCoder/sympy,mcdaniel67/sympy,Davidjohnwilson/sympy,wyom/sympy,hrashk/sympy,skidzo/sympy,wanglongqi/sympy,vipulroxx/sympy,skidzo/sympy,Titan-C/sympy,drufat/sympy,emon10005/sympy,hrashk/sympy,MridulS/sympy,farhaanbukhsh/sympy,Curious72/sympy,VaibhavAgarwalVA/sympy,aktech/sympy,Vishluck/sympy,saurabhjn76/sympy,jerli/sympy,chaffra/sympy,yashsharan/sympy,yukoba/sympy,Curious72/sympy,iamutkarshtiwari/sympy,sahmed95/sympy,rahuldan/sympy,dqnykamp/sympy,ChristinaZografou/sympy,toolforger/sympy,mcdaniel67/sympy,garvitr/sympy,pandeyadarsh/sympy,jamesblunt/sympy,ChristinaZografou/sympy,jbbskinny/sympy,cswiercz/sympy,kmacinnis/sympy,atsao72/sympy,postvakje/sympy,grevutiu-gabriel/sympy,AunShiLord/sympy,madan96/sympy,cccfran/sympy,cswiercz/sympy,pandeyadarsh/sympy,liangjiaxing/sympy,kumarkrishna/sympy,grevutiu-gabriel/sympy,abhiii5459/sympy,sampadsaha5/sympy,iamutkarshtiwari/sympy,atsao72/sympy,jbbskinny/sympy,Sumith1896/sympy,sahmed95/sympy,vipulroxx/sympy,AkademieOlympia/sympy,cccfran/sympy,kumarkrishna/sympy,postvakje/sympy,Designist/sympy,iamutkarshtiwari/sympy,sahilshekhawat/sympy,lindsayad/sympy,kaichogami/sympy,atsao72/sympy,Shaswat27/sympy,kaichogami/sympy,ga7g08/sympy,Sumith1896/sympy,mafiya69/sympy,hrashk/sympy,VaibhavAgarwalVA/sympy,beni55/sympy,wyom/sympy,sahilshekhawat/sympy,grevutiu-gabriel/sympy,Arafatk/sympy,AunShiLord/sympy,shipci/sympy,madan96/sympy,sunny94/temp,cccfran/sympy,liangjiaxing/sympy,pbrady/sympy,jaimahajan1997/sympy,emon10005/sympy,toolforger/sympy,moble/sympy,moble/sympy,hargup/sympy,kmacinnis/sympy,jerli/sympy,sampadsaha5/sympy,Gadal/sympy,Gadal/sympy,abhiii5459/sympy,oliverlee/sympy,kaushik94/sympy,Titan-C/sympy,MechCoder/sympy,AkademieOlympia/sympy,Gadal/sympy,Davidjohnwilson/sympy,bukzor/sympy,kumarkrishna/sympy,Curious72/sympy,debugger22/sympy,MechCoder/sympy,shipci/sympy,amitjamadagni/sympy,kaushik94/sympy,ChristinaZografou/sympy,liangjiaxing/sympy,garvitr/sympy,abhiii5459/sympy,mafiya69/sympy,Mitchkoens/sympy,yashsharan/sympy,shikil/sympy,meghana1995/sympy,cswiercz/sympy,drufat/sympy,jbbskinny/sympy,toolforger/sympy,MridulS/sympy,abloomston/sympy,lindsayad/sympy,Arafatk/sympy,maniteja123/sympy,pbrady/sympy,Davidjohnwilson/sympy,wanglongqi/sympy,beni55/sympy,srjoglekar246/sympy,meghana1995/sympy,Sumith1896/sympy,lidavidm/sympy,dqnykamp/sympy,flacjacket/sympy,Shaswat27/sympy,asm666/sympy,mcdaniel67/sympy,bukzor/sympy,sunny94/temp,skidzo/sympy,atreyv/sympy,maniteja123/sympy,debugger22/sympy,Designist/sympy,souravsingh/sympy,oliverlee/sympy,kaushik94/sympy,meghana1995/sympy,kevalds51/sympy,saurabhjn76/sympy,jamesblunt/sympy,abloomston/sympy,vipulroxx/sympy,asm666/sympy,wyom/sympy,jamesblunt/sympy,rahuldan/sympy,Vishluck/sympy,pandeyadarsh/sympy,maniteja123/sympy,sampadsaha5/sympy,chaffra/sympy,lindsayad/sympy,garvitr/sympy,kmacinnis/sympy,ga7g08/sympy,shikil/sympy,yukoba/sympy,aktech/sympy,diofant/diofant,yukoba/sympy,wanglongqi/sympy,farhaanbukhsh/sympy,lidavidm/sympy,saurabhjn76/sympy,aktech/sympy,atreyv/sympy,drufat/sympy,kevalds51/sympy,AkademieOlympia/sympy,souravsingh/sympy,bukzor/sympy,hargup/sympy,debugger22/sympy,shikil/sympy,Titan-C/sympy,yashsharan/sympy,skirpichev/omg,asm666/sympy,postvakje/sympy,emon10005/sympy,jaimahajan1997/sympy