Minor Dual fixes (#1117)
Minor Dual fixes (#1117)

* Fix `<<` stream output that broke its pretty formatting in a recent
  overhaul.

* Supply missing Dual/float comparison operators: for example, we had
  Dual<float, but not float<Dual.

* Add equalAll that is like equalVal, but also compares whether the
  derivs are equal (when both items being compared have derivatives).
imageworks/OpenShadingLanguage,imageworks/OpenShadingLanguage,lgritz/OpenShadingLanguage,aconty/OpenShadingLanguage,brechtvl/OpenShadingLanguage,brechtvl/OpenShadingLanguage,aconty/OpenShadingLanguage,brechtvl/OpenShadingLanguage,brechtvl/OpenShadingLanguage,imageworks/OpenShadingLanguage,imageworks/OpenShadingLanguage,aconty/OpenShadingLanguage,brechtvl/OpenShadingLanguage,aconty/OpenShadingLanguage,aconty/OpenShadingLanguage,lgritz/OpenShadingLanguage,lgritz/OpenShadingLanguage,imageworks/OpenShadingLanguage,lgritz/OpenShadingLanguage,lgritz/OpenShadingLanguage