Better error message when parsing malformed shadergroup commands
Better error message when parsing malformed shadergroup commands

imageworks/OpenShadingLanguage,svenstaro/OpenShadingLanguage,juvenal/OpenShadingLanguage,brechtvl/OpenShadingLanguage,juvenal/OpenShadingLanguage,mcanthony/OpenShadingLanguage,amartinez-cg/OpenShadingLanguage,imageworks/OpenShadingLanguage,brechtvl/OpenShadingLanguage,lgritz/OpenShadingLanguage,rlmh/OpenShadingLanguage,yaroslav-tarasov/OpenShadingLanguage,lgritz/OpenShadingLanguage,yaroslav-tarasov/OpenShadingLanguage,lgritz/OpenShadingLanguage,sjparker/OpenShadingLanguage,rlmh/OpenShadingLanguage,aconty/OpenShadingLanguage,juvenal/OpenShadingLanguage,yaroslav-tarasov/OpenShadingLanguage,sjparker/OpenShadingLanguage,rlmh/OpenShadingLanguage,aconty/OpenShadingLanguage,mcanthony/OpenShadingLanguage,aconty/OpenShadingLanguage,imageworks/OpenShadingLanguage,amartinez-cg/OpenShadingLanguage,svenstaro/OpenShadingLanguage,johnhaddon/OpenShadingLanguage,amartinez-cg/OpenShadingLanguage,amartinez-cg/OpenShadingLanguage,rlmh/OpenShadingLanguage,fpsunflower/OpenShadingLanguage,fpsunflower/OpenShadingLanguage,amartinez-cg/OpenShadingLanguage,fpsunflower/OpenShadingLanguage,sjparker/OpenShadingLanguage,johnhaddon/OpenShadingLanguage,aconty/OpenShadingLanguage,lgritz/OpenShadingLanguage,gzorin/OpenShadingLanguage,gzorin/OpenShadingLanguage,lgritz/OpenShadingLanguage,brechtvl/OpenShadingLanguage,brechtvl/OpenShadingLanguage,gzorin/OpenShadingLanguage,imageworks/OpenShadingLanguage,imageworks/OpenShadingLanguage,johnhaddon/OpenShadingLanguage,juvenal/OpenShadingLanguage,svenstaro/OpenShadingLanguage,svenstaro/OpenShadingLanguage,sjparker/OpenShadingLanguage,johnhaddon/OpenShadingLanguage,aconty/OpenShadingLanguage,brechtvl/OpenShadingLanguage,mcanthony/OpenShadingLanguage,mcanthony/OpenShadingLanguage,gzorin/OpenShadingLanguage,gzorin/OpenShadingLanguage,fpsunflower/OpenShadingLanguage,yaroslav-tarasov/OpenShadingLanguage