Open url in the default web browser.

	// EditorScript that quickly searchs for a help page
	// of the selected Object.
	//
	// If there is no page found on the Manual it opens the Unity forum.
	import UnityEditor;
	class QuickHelper extends EditorWindow {
		var source : Object;
		@MenuItem("Example/QuickHelper _h")
		static function Init() {
			var window : QuickHelper = EditorWindow.GetWindowWithRect(QuickHelper, Rect(0,0,165,100));
			window.Show();
		}
		function OnGUI() {
			EditorGUILayout.BeginHorizontal();
			source = EditorGUILayout.ObjectField(source, Object);
			EditorGUILayout.EndHorizontal();
			if(GUILayout.Button("Search!")) {
				if(source == null) {
					this.ShowNotification(GUIContent("No object selected for searching"));
				} else {
					if(Help.HasHelpForObject(source))
						Help.ShowHelpForObject(source);
					else
						Help.BrowseURL("http://forum.unity3d.com/search.php");
				}
			}
		}
	}