I fixed Kane's bugs of auxiliary speeds.
I fixed Kane's bugs of auxiliary speeds.

When I used the auxiliary speeds of wheel-ground contact points
to obtain contact forces in physics.mechanics using kane's method
class, I confronted bugs which did not pop up correct forces. We
tried to suspect the _mat_inv_mul function, and then fixed dummy
symbols.

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