Nilpotency testing, improved solvability testing.
Nilpotency testing, improved solvability testing.

And minor fixes in several docstrings.

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