AddDrawer adds layout as drawer on a given side.
		
		If the user swipes from this side to the other the layout will slide out.
		
		See Also: OpenDrawer, CloseDrawer, RemoveDrawer
		
			Example - left
			
				function OnStart()
				{
				    lay = app.CreateLayout( "Linear", "FillXY,VCenter" );
				    
				    txt1 = app.CreateText( "<-- swipe" );
				    txt1.SetTextSize( 30 );
				    lay.AddChild( txt1 );
				    
				    app.AddLayout( lay );
				    
				    layDrawer = app.CreateLayout( "Linear", "FillXY,VCenter" );
				    layDrawer.SetBackground( "/Sys/Img/BlueBack.jpg" );
				    
				    txt2 = app.CreateText( "Hello" );
				    txt2.SetTextSize( 40 );
				    layDrawer.AddChild( txt2 );
				    
				    app.AddDrawer( layDrawer, "left", 0.8 );
				}