combsimp: new mult_thm algorithm
combsimp: new mult_thm algorithm

- no simplification of differences is done
- this routine does not depend on the terms being sorted

You can see the failure of the implementation before this commit
by changing _sorted_args to args in

newargs = list(cexpr._sorted_args) if not cexpr.is_Atom else [cexpr]

and running tests in 2.7 with PYTHONHASHSEED=4251385681

The result obtained for the test at line 1091 in test_simplify will
be different and if you check the value at x=2 you will see that
it does not agree with the value of the original expression.

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