added _eval_power to IdentityOperator to avoid unevaluated expressions like I**2
added _eval_power to IdentityOperator to avoid unevaluated expressions like I**2

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