Added the matplotlib backend for implicit plotting
Added the matplotlib backend for implicit plotting

The backend uses contourf to plot the 2d array returned by get_meshes().
contourf implements the marching square algorithm and hence the plots are
less rasterized.

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