Added more useful extensions
Added more useful extensions

AngleSharp/AngleSharp,FlorianRappl/AngleSharp,AngleSharp/AngleSharp,AngleSharp/AngleSharp,FlorianRappl/AngleSharp,FlorianRappl/AngleSharp,AngleSharp/AngleSharp,FlorianRappl/AngleSharp,AngleSharp/AngleSharp