Add parametric option to bound_degree()
Add parametric option to bound_degree()

The parametric and non-parametric cases are all exactly identical for
the regular Risch Differential Equation and parametric Risch
Differential Equation, except for the former dc = c.degree(t) and in the
latter, dc = max([i.degree(t) for i in G]).

Other algorithms in prde.py are very similar to their counterparts in
rde.py, and could probably also benefit from such consolidation, though
none are as close as this one.

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