Print unnamed Dummy symbols more prominently
Print unnamed Dummy symbols more prominently

Previously, they were just printed as _12 or pretty printed as just 12, which
looked like a number in an expression.  This way, if a Dummy leaks out, it is
clear.

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