DiagramGrid: Sort the vertices in the root triangle.
DiagramGrid: Sort the vertices in the root triangle.

Previously DiagramGrid would not sort the vertices in the edges of
the first triangle, out of which the root edge was picked.  This resulted
in different edges being sometimes picked, as well arbitrary positioning
of the vertices of the root edge.

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