numbers: implement direct __abs__ & __neg__ for singletons where appropriate
numbers: implement direct __abs__ & __neg__ for singletons where appropriate

from operator import abs as abs_


        %timeit     %timeit     %timeit     ...
        abs_(pi)    -S.One        -oo

old:    36.1 µs     23.2 µs     22.2 µs
new:     2.7 µs      2.6 µs      2.4 µs

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