P and D as inputs produces some errors

[mayersre]

When I try to use P and D as inputs

PropsSI("H","P",50000,"D",1.246319665,"R134a") should give a result

I get :
ValueError: Inputs in Brent [218.150000,456.000000] do not bracket the root. Function values are [-28172.007837,-3777.868867] : PropsSI("H","P",50000,"D",1.246319665,"R134a")

same call to refprop brings a result :
cp.PropsSI("H","P",50000,"D",1.246319665,"REFPROP::R134a")
620114.7787468057

[ibell]

According to http://www.coolprop.dreamhosters.com:8010/sphinx/_downloads/R134a1.pdf it seems there are a few problems with D,P inputs for R134a

Also it seems that we should log scale the densities, a lot of the points are hiding and it is hard to see if there were any issues. See #275

[ibell]

Temperature is above the maximum for the EOS

[ibell]

Closed by de6e95e